Genetic Predisposition to Solid Pediatric Cancers

A cervical rib (CR), also known as a supernumerary or extra rib, is an additional rib that forms above the first rib, resulting from the overgrowth of the transverse process of a cervical vertebra. Increasingly recognized as a potential marker of developmental disruptions and genetic instability, CRs are believed to arise from mutations in homeobox (Hox) genes that influence axial skeletal development. While often asymptomatic, CRs have been linked to thoracic outlet syndrome and a higher prevalence in individuals with certain childhood cancers. Studies have reported associations between CRs and malignancies such as neuroblastoma, brain tumors, leukemia, sarcomas, Wilms tumor, and germ cell tumors, suggesting possible shared embryological pathways or genetic predispositions. However, conflicting research findings highlight inconsistencies in these associations, underscoring the need for further investigation. This review aims to assess the association between CRs and childhood cancers by examining prevalence rates, exploring genetic and developmental links, evaluating inconsistencies in existing research, and identifying gaps for future study to clarify the clinical significance of CRs in cancer risk assessment. Introduction A Cervical rib (CR), also known as a "neck rib" or "supernumerary rib," is an extra rib that forms above the first rib, near the collarbone. It develops due to an overgrowth of the transverse process of a cervical spine vertebra. It is thought to result from mutations in homeobox (Hox) genes, which play a role in shaping the axial skeleton in humans and vertebrates. This rib can occur on either side and may be unattached (floating) or fused with the first rib. It can range from a fully formed bone to a delicate fibrous strand [1]. The CRs are present in about 2% of the general adult population. The prevalence is higher in women, who are about twice as likely to have CRs as men. Additionally, ethnic differences have been observed, with one study finding that CRs are more common in African Americans than in whites [2]. Typically, CR is discovered incidentally through radiographic imaging unless it causes symptoms [3]. In some cases, CR can contribute to thoracic outlet syndrome by narrowing the interscalene triangle, leading to pain, weakness, numbness, or cold sensitivity in the affected limb [1, 4, 5]. The first documented clinical signs of neurovascular compression associated with CRs were reported by Cooper in 1818 [6]. Studies have demonstrated a higher prevalence of CRs in individuals with childhood cancers. This association may stem from disruptions in embryonic development during critical stages of blastogenesis, which can simultaneously lead to cervical segmentation defects and increase cancer susceptibility [7, 8]. Moreover, CRs are often regarded as markers of adverse developmental events or genetic instability. Their higher prevalence in stillborn fetuses and individuals with chromosomal abnormalities further underscores their potential role as indicators of systemic vulnerabilities that may contribute to malignancy risk. These findings highlight the importance of understanding rib anomalies (RAs) as anatomical curiosities and potential markers for identifying individuals at increased risk for certain cancers [9]. This study aims to review the association between CRs and cancer, with all referenced articles assessed for eligibility [10]. Studies Linking Rib Anomalies to Childhood Cancers Despite growing awareness of a possible connection between RAs and malignancies, research on this topic remains limited. Only four studies have examined this association, each providing valuable insights into the potential link. The earliest study by Schumacher et al. (1995) investigated the relationship between RAs and childhood malignancies by reviewing chest X-rays of 1,000 children with cancer and 200 control patients with non-malignant conditions. They found a significantly higher prevalence of RAs, particularly CRs, in children with certain malignancies compared to controls. This suggested that these skeletal abnormalities might be linked to altered morphogenesis in tumor development [7]. A decade later, Merks et al. (2005) conducted a more extensive study analyzing chest radiographs of 906 children with cancer and 881 healthy Caucasian pediatric controls. Their findings confirmed previous reports, demonstrating a higher occurrence of specific RAs in children with certain malignancies. They emphasized the potential role of genetic predisposition in cancer development and suggested that skeletal anomalies could serve as markers for underlying genetic abnormalities [8]. Loder et al. (2007) expanded on these findings by focusing on rib number variations in 218 children with malignancies and 200 control children who had been admitted for polytrauma or suspected child abuse. Their study highlighted a significant difference in rib counts between children with cancer and healthy controls. They speculated that genes involved in vertebral and rib development might also play a role in cancer predisposition, suggesting the possibility of using skeletal anomalies as a screening tool for early cancer detection [11]. Finally, Zierhut et al. (2011) reinforced the association between RAs and childhood cancers through a hospital-based case-control study of 459 pediatric cancer patients and 1,135 controls who had undergone chest X-rays for non-cancer-related reasons. Their research confirmed that children with cancer were more likely to have RAs, particularly those diagnosed with specific malignancies. They underscored the need for further studies to determine the biological mechanisms linking RAs to cancer development [12]. Cancers Linked to Cervical Ribs Neuroblastoma Neuroblastoma is a highly aggressive tumor that develops from neural crest cells and is the most common cancer in infants under one year old worldwide [13]. It represents about 10% of all pediatric cancers and primarily affects children within their first five years of life [14]. A defining characteristic of neuroblastoma is its highly variable clinical behavior. In approximately 50% of affected infants, the tumor regresses spontaneously, whereas in others, it advances into an aggressive, metastatic disease that is often resistant to standard treatments like chemoradiotherapy, stem cell transplantation, and immunotherapy [15]. This unpredictability complicates treatment, especially for high-risk patients who experience chemo-resistant relapse, with survival rates remaining below 40% [14]. The initiation and progression of neuroblastoma are driven by genetic abnormalities that interfere with cell division, proliferation, and apoptosis [15]. Significant genetic factors include MYCN amplification, TP53 deletions, ALK mutations or amplifications, TERT rearrangements, ATRX deletions or mutations, and segmental chromosomal aberrations. However, whole-genome sequencing studies have identified only a limited number of recurrent somatic mutations, making the development of targeted therapies challenging. Consequently, a precise understanding of the biological complexity and diversity of neuroblastoma is crucial for improving diagnostic and treatment approaches [15]. Schumacher et al. (1992) identified a strong correlation between neuroblastoma and CRs, reporting that 33% of children with neuroblastoma had CRs, a markedly higher prevalence than in the general population. This notable disparity suggests a potential developmental or genetic connection between neuroblastoma and skeletal anomalies. Furthermore, neuroblastoma was the only malignancy in their study to exhibit a significantly increased incidence of rib bifurcation (4.5%), a rate nearly four times higher than expected, reinforcing the possibility of disrupted skeletal development linked to the disease [7]. In contrast, Merks et al. (2005) analyzed 61 neuroblastoma patients and found that 9.8% had CRs, compared to 6.1% in the control group. While this suggests a slightly increased prevalence, the difference was not statistically significant (p = 0.252). This discrepancy with Schumacher et al. (1992) may be due to differences in sample size, diagnostic criteria, or population characteristics [7, 8]. Loder et al. (2007) took a broader approach by grouping neuroblastoma with other neural malignancies. Their findings showed a higher incidence of RAs (35%) in children with neural tumors compared to those with other malignancies. However, they did not specifically find an association between neuroblastoma and CRs. Among the eight neuroblastoma patients in their study, RAs were present, but no cases of CRs were observed. Instead, the most common skeletal abnormality was a reduced rib count, with affected children having 22 or 23 ribs instead of the typical 24. This suggests that while RAs may be linked to neuroblastoma, the specific presence of CRs may not be a defining characteristic [11]. Similarly, Zierhut et al. (2011) analyzed 31 neuroblastoma cases and found that 6.4% had RAs. However, the study did not report how many of these cases involved CRs specifically. The statistical analysis yielded an odds ratio (OR) of 1.46 (95% CI: 0.34–6.30) for any rib anomaly in neuroblastoma patients, indicating a slightly higher occurrence of skeletal abnormalities but without statistical significance. The lack of a significant association between RAs and neuroblastoma may be due to the study’s small sample size, which could have limited its ability to detect a stronger relationship [12]. Overall, while Schumacher et al. (1992) identified a strong association between neuroblastoma and CRs, subsequent studies, including those by Merks et al. (2005), Loder et al. (2007), and Zierhut et al. (2011), reported weaker or non-significant links [7, 8, 11, 12]. The inconsistencies across studies highlight the need for further research with larger sample sizes and more detailed skeletal analyses to determine whether CRs represent a meaningful developmental marker for neuroblastoma or if their observed association is due to broader skeletal anomalies. Brain Tumors A brain tumor forms when cells grow irregularly and multiply uncontrollably. These tumors may arise from brain cells, the meninges (the membranes surrounding the brain), glands, or nerves. They can cause direct damage to brain cells and elevate pressure within the skull, resulting in harmful effects [16]. Due to their severity, brain tumors are classified into different grades. Grade 1 tumors are the least aggressive, typically associated with more prolonged survival. They grow slowly, resemble normal cells under a microscope, and can often be effectively treated with surgical removal. Examples include pilocytic astrocytoma, ganglioglioma, and gangliocytoma. Grade 2 tumors also grow slowly but appear abnormal under a microscope. Some may invade nearby tissues and tend to recur, occasionally progressing to a higher grade [16]. Grade 3 tumors are malignant and share similarities with grade 2 tumors but are more likely to recur as grade 4 tumors. Grade 4 tumors are the most aggressive, growing rapidly and appearing highly abnormal under a microscope. They invade surrounding brain tissue, form new blood vessels, and contain areas of dead cells at their core. Glioblastoma Multiforme is a well-known example of a grade 4 tumor [16]. Brain tumors develop due to a combination of genetic, environmental, and molecular factors. Genetic predisposition plays a key role, with inherited syndromes such as neurofibromatosis and Li-Fraumeni syndrome increasing the risk. Environmental exposures, particularly ionizing radiation, are well-established contributors, while occupational exposure to chemicals and electromagnetic fields remains inconclusive. Viral infections, immune dysfunction, and chronic inflammation may also influence tumor development [17, 18]. The study by Schumacher et al. (1992) found that 27.4% of children with brain tumors had CRs, compared to only 5.5% in the control group (p < 0.001). This substantial difference suggests a potential developmental link between CRs and brain tumors, possibly due to shared embryological pathways affecting both skeletal and neural development. The high prevalence reported in this study indicates that CRs might serve as an anatomical marker for underlying genetic or developmental disruptions associated with brain tumor formation [7]. Merks et al. (2005) further supported this hypothesis by identifying a significant association between CR anomalies and astrocytomas. Their study reported that 18.2% of childhood cancer patients with astrocytomas had CRs, compared to 6.1% in the control group. This finding suggests that certain subtypes of brain tumors, particularly astrocytomas, may have a stronger developmental association with CR anomalies [8]. However, Loder et al. (2007) did not find a strong link between brain tumors and CRs. While RAs were more frequent in children with neural malignancies (35%), none of these anomalies were identified as CRs. Instead, children with neural malignancies were found to be 6.23 times more likely to have an abnormal rib count compared to the control group. This suggests that while skeletal anomalies may be associated with neural tumors in general, CRs specifically may not be a consistent marker [11]. Zierhut et al. (2011) also provided a more tempered perspective. Their study examined 34 pediatric cases of central nervous system tumors, including brain tumors, and found that 8.8% (n = 3) had some form of rib anomaly. However, they did not identify a statistically significant association between CRs and brain tumors. This finding further weakens the case for a direct link and suggests that broader skeletal anomalies may be involved rather than CRs specifically [12]. Overall, while Schumacher et al. (1992) and Merks et al. (2005) suggest a possible association between CRs and brain tumors, the findings from Loder et al. (2007) and Zierhut et al. (2011) cast doubt on the specificity of this relationship [7, 8, 11, 12]. The inconsistencies across studies highlight the need for further research to determine whether CRs are a true marker for brain tumor risk or if their association is due to broader developmental abnormalities affecting multiple organ systems. Leukemia Leukemia is a frequently occurring cancer in both children and adults. It results from disruptions in normal cell regulation that lead to the uncontrolled growth of hematopoietic stem cells in the bone marrow. It is more commonly found in males and individuals of white ethnicity, with its prevalence increasing with age. On average, about one in 70 people will develop leukemia during their lifetime. The four main types of leukemia, each with unique characteristics, are acute lymphoblastic leukemia (ALL), acute myelogenous leukemia (AML), chronic lymphocytic leukemia, and chronic myelogenous leukemia [19]. Leukemia occurs worldwide, with a higher prevalence and overall mortality in more developed countries. However, the mortality rate tends to be greater in developing nations [20]. The development of leukemia results from a complex interaction between genetic predisposition and environmental influences, with neither factor alone provides a complete explanation. While significant strides have been made in identifying risk factors and potential disease mechanisms, the exact causes of most leukemia cases remain uncertain. Known risk factors include genetic syndromes, chromosomal abnormalities, radiation exposure, specific chemicals, certain viral infections, and prior cancer treatments, but these account for only a fraction of cases [20, 21]. The study by Schumacher et al. (1992) found a significant association between CRs and leukemia, with 26.8% (n = 227) of leukemia patients exhibiting CRs compared to only 5.5% (n = 11) in the control group (p < 0.001). This finding suggests a potential developmental or genetic link between skeletal anomalies and leukemia, possibly due to disruptions in early embryonic development affecting both hematopoietic and skeletal systems [7]. Similarly, Merks et al. (2005) identified a significant association between CR anomalies and ALL, with a prevalence of 12.1% in ALL patients compared to 6.1% in controls (p = 0.011). This reinforces the idea that skeletal anomalies may serve as a marker for certain pediatric malignancies, though the underlying mechanisms remain unclear [8]. Loder et al. (2007) further examined RAs in leukemia patients. Among 218 children with malignancies, 75 had leukemia (64 with ALL and 11 with AML) [11]. The incidence of abnormal rib counts in children with lymphoproliferative malignancies (which includes leukemia and lymphoma) was 15%, compared to 8% in the control group. Logistic regression analysis revealed that children with leukemia and other lymphoproliferative malignancies were twice as likely to have an abnormal rib count compared to controls. While this supports a broader association between RAs and leukemia, the study did not specifically focus on CRs, making direct comparisons with Schumacher et al. (1992) and Merks et al. (2005) more challenging [7, 8]. In contrast, Zierhut et al. (2011) provided a more nuanced perspective. While their study confirmed an overall link between RAs and an increased risk of childhood cancers, the specific association between CRs and leukemia did not reach statistical significance. Notably, children with AML had a significantly higher likelihood of RAs, with an adjusted OR of 2.29 (95% CI: 1.02–5.13). However, when CRs were analyzed separately, the association weakened (adjusted OR = 1.63, 95% CI: 0.55–4.80), failing to reach statistical significance. This suggests that while RAs in general may be linked to leukemia, CRs alone may not be a consistent marker for the disease [12]. Overall, the studies by Schumacher et al. (1992) and Merks et al. (2005) suggest a potential association between CRs and leukemia [7, 8, 11]. However, Zierhut et al. (2011) cast doubt on the specificity of this relationship, indicating that while RAs may be more common in leukemia patients, CRs alone may not be a reliable marker [12]. Further research is needed to clarify whether CRs are a developmental indicator of leukemia risk or if their observed association is due to broader skeletal anomalies linked to pediatric malignancies. Sarcomas Sarcomas comprise a diverse group of mesenchymal tumors, with over 100 distinct diagnostic types. This variability is evident through both light microscopy and gene expression analysis. Even within the same histological category, there can be substantial differences in biological behavior [22]. Sarcomas are generally classified into two main types: soft tissue sarcomas and primary bone sarcomas, each requiring unique staging and treatment strategies. Soft tissue sarcomas are typically categorized based on genetic alterations and microscopic examination of hematoxylin-eosin–stained tissue, where morphological features resembling normal tissues are identified. Additionally, sarcomas are further assessed by histologic grade. The three key prognostic factors are the tumor’s grade, size, and primary location [22]. Sarcomas usually arise spontaneously, but certain risk factors have been identified. Exposure to ionizing radiation, often from cancer treatments, increases the likelihood of sarcomas, typically appearing 7-10 years after exposure. Other risk factors include chronic lymphedema, exposure to chemicals like vinyl chloride, and infection with human herpesvirus 8, which is linked to Kaposi sarcoma [22]. Several genetic syndromes also elevate sarcoma risk. Neurofibromatosis type 1 leads to benign and malignant nerve sheath tumors, while neurofibromatosis type 2 is associated with meningiomas and cranial nerve schwannomas. Gardner syndrome increases the risk of desmoid tumors, and hereditary retinoblastoma raises the likelihood of osteosarcoma and soft tissue sarcomas later in life. Li-Fraumeni syndrome, caused by TP53 mutations, also predisposes individuals to sarcomas [22]. Schumacher et al. (1992) found a significant association between CRs and sarcomas, reporting their presence in 24.5% of patients with soft tissue sarcomas (p < 0.001) and 17.1% of those with Ewing sarcoma (p < 0.01), compared to only 5.5% in the control group. These findings suggest a potential developmental or genetic link between CR anomalies and sarcomas, possibly due to early mesodermal development disruptions, which influences skeletal and soft tissue formation [7]. However, later studies did not consistently replicate these findings. Merks et al. (2005) found much lower rates of CRs in sarcoma patients, with 7.4% of rhabdomyosarcoma cases (5/68, p = 0.687), 6.3% of osteosarcoma cases (3/48, p = 0.973), and 7.7% of Ewing sarcoma cases (3/39, p = 0.692). None of these differences were statistically significant, suggesting that the initial association reported by Schumacher et al. (1992) may have been due to sample variation or other confounding factors. The stark contrast between these two studies raises questions about whether the observed link is truly biologically relevant or if it was an artifact of study design or population differences [8]. Loder et al. (2007) examined RAs in solid tumors, including osteosarcoma, rhabdomyosarcoma, and Ewing sarcoma, finding that 13% of cases exhibited RAs. However, this association was not statistically significant (p = 0.15), suggesting that while RAs may be more common in children with cancer, they do not appear to be strongly associated with sarcomas specifically [11]. Similarly, Zierhut et al. (2011) identified a general link between RAs and childhood cancers but did not find a significant correlation between CRs and sarcomas. This further weakens the hypothesis that CRs are a marker for sarcoma risk [12]. Overall, while the Schumacher et al. (1992) study initially suggested a strong association between CRs and sarcomas, more recent studies, including those by Merks et al. (2005), Loder et al. (2007), and Zierhut et al. (2011), have not confirmed this relationship [7, 8, 11, 12]. The inconsistencies in findings suggest that if a link does exist, it may be weaker than initially thought or influenced by confounding factors. Further research with larger sample sizes and refined methodologies is needed to clarify whether CRs have any true predictive value for sarcoma development. Wilms tumor Wilms tumor (WT), or nephroblastoma, is a malignant solid tumor that arises from the primitive renal bud. It is the most common primary renal tumor in the urogenital tract of children and typically occurs unilaterally in 90–95% of cases. However, it can also present bilaterally or multicentrically, particularly in cases associated with genetic factors, occurring either simultaneously (synchronously) or at different times (metachronously). WT accounts for approximately 2% to 6% of all childhood cancers [23]. Both genetic and environmental factors influence the development of WT. Genetic mutations play a crucial role, particularly in the WT1 and WT2 genes, which are vital for kidney development [23]. WT1 mutations are linked to syndromic forms of WT, such as WAGR and Denys-Drash syndromes, while WT2 abnormalities are associated with Beckwith-Wiedemann syndrome. Additionally, mutations in CTNNB1 (β-catenin), TP53, and microRNAs contribute to tumor development. Environmental factors, including parental exposure to pesticides before conception or during pregnancy, may increase the risk, though their precise impact remains unclear. WT is frequently associated with congenital syndromes involving developmental abnormalities [23]. Schumacher et al. (1992) identified a significant association between CRs and WT, reporting that 23.5% of children with WT had CRs, compared to only 5.5% in the control group (p < 0.001). This strong statistical significance suggests a potential developmental link between skeletal anomalies and WT [7]. However, Merks et al. (2005) found that 9.8% of children with WT had CRs, compared to 6.1% in the control group, but the difference was not statistically significant (p = 0.115). This suggests that while CRs may be more common in WT patients, the association is not robust enough to be considered a reliable marker [8]. Similarly, Zierhut et al. (2011) reported a statistically significant increase in overall RAs among children with renal tumors, including WT. However, when analyzing CRs specifically, they did not find a significant association, further casting doubt on their role as a consistent indicator of WT [12]. Loder et al. (2007) provided additional support for a general link between RAs and pediatric malignancies but did not specifically analyze CRs in WT patients. This broader pattern suggests that skeletal anomalies may be associated with childhood cancers but does not confirm a direct link between CRs and WT [11]. These findings indicate that while there is some evidence of a relationship between skeletal anomalies and WT, the inconsistent association with CRs suggests that other factors may be at play. Additional research is needed to explore the genetic and developmental mechanisms underlying these observations, which could provide further insights into the etiology of WT and its potential links to congenital anomalies. Germ Cell Tumors Germ cell tumors (GCTs) are the most diverse childhood neoplasms. The majority are benign teratomas, presenting as heterogeneous masses with cystic and solid components. However, approximately 20% of GCTs are malignant, accounting for 3% of pediatric cancers. Malignant GCTs can occur at any age but follow a bimodal distribution, primarily affecting infants and adolescents [24]. These tumors can develop in various anatomical locations, including the gonads, sacrococcygeal region, mediastinum, retroperitoneum, and other para-axial sites. They are believed to originate from a common progenitor germ cell but exhibit diverse histologies, such as endodermal sinus tumor (yolk sac tumor), germinoma (dysgerminoma or seminoma), embryonal carcinoma, and choriocarcinoma. Different histological types often coexist within a single tumor, with approximately 25% of pediatric GCTs containing multiple histologic components [24]. Malignant GCTs have specific genetic predispositions, and genome-wide association studies (GWAS) have identified single-nucleotide polymorphisms (SNPs) in genes such as KITLG, SPRY4, DMRT1, and TERT, which are linked to the development of testicular GCTs [25]. Schumacher et al. (1992) investigated the relationship between CR anomalies and yolk sac tumors, a type of GCT, but did not find a significant association. The prevalence of RAs in patients with yolk sac tumors was 3.4%, which was not significantly different from the normal population (5.5%). This finding suggests that, unlike other pediatric malignancies, GCTs may not share a strong developmental link with skeletal anomalies [7]. In contrast, Merks et al. (2005) reported a statistically significant association between CR anomalies and GCTs, with 14.7% of GCT patients exhibiting CRs compared to 6.1% in controls (p = 0.046). This suggests a potential genetic or developmental link between GCTs and skeletal anomalies, though the mechanisms underlying this association remain unclear. The higher prevalence observed in this study raises the possibility that certain genetic mutations or disruptions in embryonic development may predispose individuals to both conditions [8]. Loder et al. (2007) did not specifically analyze CRs in relation to GCT. However, their study demonstrated a broader statistically significant association between RAs and childhood malignancies. Children with cancer had a higher prevalence of RAs (18%) compared to the control group (8%), with a p-value of 0.003. While this finding supports a general link between skeletal anomalies and pediatric cancers, it does not establish a direct connection between CRs and GCTs [11]. Similarly, Zierhut et al. (2011) did not specifically report a link between CR and GCTs. The absence of a reported association with GCTs suggests that these tumors may not be as strongly linked to skeletal anomalies as other childhood malignancies [12]. Overall, while some studies indicate a potential link between CR anomalies and GCTs, the evidence remains inconsistent. Merks et al. (2005) provided the most substantial support for an association, but findings from Schumacher et al. (1992) and Zierhut et al. (2011) did not confirm this relationship [7, 8, 12]. Additional research is needed to determine whether CR anomalies can serve as a marker for GCTs or if the observed association is due to other underlying developmental factors. Other Rib Anomalies Associated with Cancer Numerical RAs, such as having fewer than 24 ribs, were also found to be more common in children with malignancies. Loder et al. (2007) reported that 18% of children with malignancies had an abnormal rib number compared to 8% of controls. Among specific cancer types, neural tumors had the highest incidence of abnormal rib counts (35%), followed by lymphoproliferative malignancies (15%) and solid tumors (13%) [11]. Similarly, Zierhut et al. (2011) found that children with AML, renal tumors, and hepatoblastoma had a significantly higher likelihood of having an abnormal rib count (p = 0.008) [12]. Rib bifurcations, which involve rib splitting into two separate structures, have also been linked to certain malignancies. Schumacher et al. (1992) reported that 4.5% of neuroblastoma patients exhibited rib bifurcations, a rate four times higher than that of the normal population (1.07%). This suggests that developmental abnormalities affecting rib segmentation may be related to tumorigenesis in neural crest-derived cancers such as neuroblastoma [7]. Rib synostosis, or rib fusion, has also been observed in childhood malignancies. Though relatively rare, this anomaly was documented in some studies. Schumacher et al. (1992) found that 0.5% of cancer patients had rib synostosis compared to none in the control group, while Merks et al. (2005) identified synostosis in 0.2% of cancer patients. Notably, leukemia and brain tumor patients were more likely to present with this anomaly [7, 8]. Additionally, rib hypoplasia (underdeveloped ribs) and aplasia (missing ribs) have been reported in association with various malignancies. Loder et al. (2007) found that children with malignancies were more likely to have fewer ribs, with 44 cases of 22 ribs and 10 cases of 23 ribs, compared to just 16 cases in the control group (p = 0.003) [11]. Schumacher et al. (1992) also reported that 1.2% of cancer patients had rib aplasia or hypoplasia, compared to 0.5% in controls (Table 1) [7]. Table 1. Association Between Rib Anomalies and Childhood Malignancies. Study Year Sample Size Key Findings Cancer Types Types of Rib Anomalies Conclusion Schumacher et al. [7] 1992 1000 cancer, 200 controls Rib anomalies more common in cancer patients (21.8% vs. 5.5% in controls). Neuroblastoma had the highest rate (33%). Neuroblastoma, Brain tumors, Leukemia, Soft tissue sarcoma, Wilms' tumor, Ewing sarcoma CRs, Bifurcations, Synostoses, Aplasia/Hypoplasia Rib anomalies may be linked to tumor development. Further research needed. Merks et al. [8] 2005 906 cancer, 881 controls CRs were more common in cancer patients (8.6% vs. 6.1% in controls), particularly in leukemia and astrocytoma. ALL, Astrocytoma, Germ Cell Tumors CRs, Bifid ribs, Rib synostosis Rib anomalies could indicate genetic mutations linked to cancer. Loder et al. [11] 2007 218 cancer, 200 controls Rib anomalies were more frequent in cancer patients (18% vs. 8%). Neural tumors had the highest incidence (35%). Neural tumors, Lymphoproliferative malignancies, Solid tumors Fewer than 24 ribs, Rib fusions, Bifurcations Possible link between rib anomalies and homeobox gene mutations. Zierhut et al. [12] 2011 625 cancer, 1499 controls Significant association found between rib anomalies and leukemia, renal tumors, and hepatoblastoma. AML, Renal tumors, Hepatoblastoma Fewer or more than 24 ribs, CRs, Bifurcations Rib anomalies could be a marker for cancer predisposition. More research needed. ALL: Acute Lymphoblastic Leukemia, AML: Acute Myelogenous Leukemia, CR: Cervical rib Future Perspectives Future research should focus on large-scale, multicenter studies to validate these findings and establish whether RAs, particularly numerical variations, bifurcations, synostoses, and hypoplasia, can be predictive markers for specific cancers. Advances in imaging technologies, such as high-resolution computed tomography and magnetic resonance imaging, may enhance the accuracy of rib anomaly detection and contribute to more precise correlations with cancer risk. Genetic and molecular studies are also needed to explore the role of Hox genes and other developmental pathways in skeletal formation and oncogenesis. Identifying genetic mutations contributing to RAs and tumor development could lead to novel insights into cancer predisposition syndromes. Additionally, investigating the role of environmental and epigenetic factors in the occurrence of RAs and malignancies may provide a more comprehensive understanding of their shared etiology. From a clinical perspective, integrating rib anomaly screening into routine pediatric check-ups for high-risk populations could help in early cancer detection. However, before implementing such screening, further studies must determine the predictive value of RAs and whether they can be used as independent risk markers. Ultimately, interdisciplinary collaboration between geneticists, radiologists, oncologists, and developmental biologists will be crucial in advancing understanding of the link between RAs and childhood cancer. As research continues, these efforts may pave the way for novel diagnostic strategies and targeted therapies for pediatric malignancies. Conclusion CRs may serve as valuable indicators of underlying genetic and developmental abnormalities linked to pediatric cancers. Understanding these connections could ultimately contribute to improved cancer screening, early diagnosis, and personalized treatment strategies for children at risk. Declarations Conflicts of interest: The authors have no conflicts of interest to disclose. Ethical approval: Not applicable. Patient consent (participation and publication): Not applicable. Funding: The present study received no financial support. Acknowledgements: None to be declared. Authors' contributions: FHK and BAA were significant contributors to the conception of the study and the literature search for related studies. HAN and MNH involved in the literature review, study design, and manuscript writing. SKA, AKG, WNS, HSN, LJM, ASH, OMH, SOA, AHA, LAS and ADS were involved in the literature review, data collection, the study's design, and the critical revision of the manuscript. FHK and BAA confirm the authenticity of all the raw data. All authors approved the final version of the manuscript. Use of AI: Perplexity (Deep Research) and ChatGPT (GPT-4.5) were used to assist in language editing and improving the clarity of the manuscript. All content was reviewed and verified by the authors. Authors are fully responsible for the entire content of their manuscript. Data availability statement: Not applicable.

Introduction: Recurrent somatic alterations associated with pediatric, childhood, and young adult cancers have not been as intensively studied as those associated with adult cancers. Consequently, whole-exome and transcriptome approaches are still being used to support discovery efforts. However, due to several initiatives aimed at profiling genomic alterations associated with childhood cancers, a set of recurrent somatic alterations has been defined. To accelerate research in this area, we have developed a novel targeted next-generation sequencing (NGS) assay to detect relevant somatic alterations previously reported in these cancer types. Methods: The assay was developed using Ion AmpliSeq targeted sequencing technology to cover the major gene variants associated with childhood cancers, including both solid tumor and hematologic cancer types. Over 200 gene targets were included on the basis of consultation with expert pediatric oncologists, literature review of the recent pediatric cancer genomic publications, as well as inclusion of relevant markers from adult cancers that are also observed in childhood cancers. Variant classes include mutations, copy number variations, gene fusions, and gene expression. Mutations in 130 genes, copy number variants in 28 genes, and over 1,400 distinct fusion isoforms in 88 fusion driver genes are analyzed. Variant calling algorithms for both DNA and RNA were optimized and combined into a single Ion Reporter workflow. Results: The assay generated an average read depth of >3,000 reads per DNA amplicon with high uniformity (>95%), when up to 7 sample DNA-RNA pairs were analyzed with the 540 chip of the Ion S5 sequencing instrument. Minimal allele frequency detected for key hotspots was 5%. Sensitive and reproducible detection of CNV and fusion variants associated with pediatric solid tumors (EWSR1-FL1 and KIAA1549-BRAF fusions, MYC and EGFR amplification) and hematologic cancers (ETV6-RUNX1 and PML-RARA fusions) was demonstrated in orthogonally profiled FFPE, blood, and bone marrow samples. Performance was robust across sample types. Similar results were observed with manual and automated library preparation. Conclusions: A novel NGS assay, designed specifically for pediatric, childhood, and young adult cancers, and capable of detecting relevant DNA and RNA alterations from the same sample, was developed and validated. The assay is useful for characterizing relevant alterations in a wide range of cancers, including childhood leukemias and lymphomas as well as solid tumors including neuroblastoma, rhabdomyosarcoma, retinoblastoma, osteosarcoma, Ewing sarcoma, Wilms tumor, and brain and spinal cord tumors. A review of the analytical studies will be presented. Citation Format: Nickolay A. Khazanov, Chaitali Parikh, Habib Hamidi, Scott P. Myrand, Efren Ballesteros-Villagrana, Jingwei Ni, Paul D. Williams, Karen L. Clyde, Dinesh Cyanam, Armand Bankhead, III, Manimozhi Manivannan, Mark Tomilo, Susan Ewald, Jon K. Sherlock, Janice K. Au-Young, Jaclyn Biegel, Jonathan Buckley, Matthew Hiemenz, Dejerianne Ostrow, Alex Judkins, Xiaowu Gai, Tracy Busse, Alan Wayne, Deepa Bhojwani, Raca Gordana, Matthew Oberley, David Parham, Seth Sadis, Timothy Triche. Development of a next-generation sequencing (NGS) assay for pediatric, childhood, and young adult cancer research with comprehensive DNA and RNA variant detection [abstract]. In: Proceedings of the AACR Special Conference: Pediatric Cancer Research: From Basic Science to the Clinic; 2017 Dec 3-6; Atlanta, Georgia. Philadelphia (PA): AACR; Cancer Res 2018;78(19 Suppl):Abstract nr B45.

Background: Wilms Tumor (WT) is the most common pediatric kidney cancer and in approximately 2% of cases presents a familial predisposition. In both sporadic and inherited WT cases, several genes have been identified as being somatically mutated. The most frequent WT mutated genes are WT1, CTNNB1 and WTX, that together account for approximately 30% of cases. In addition, mutation in other genes such as TP53, IGF2, DIS3L2, FBXW7, MYCN, and DICER have also been described in few cases. However, up to 60-70% of Wilms tumors remain without any associated driver mutation. In this sense, the aim of this project was to identify novel somatic and de novo alterations possibly associated with WT tumorigenesis through exome sequencing. Methods: The study design consisted of performing exome sequencing of 4 samples related to a sporadic WT patient: patient blood and tumor samples, in addition to mother's and father's blood samples. Coding regions of genomic DNA were enriched using SureSelect Human All Exon 50Mb Kit (Agilent). Libraries construction and sequencing at SOLiD 4 and 5500xl were performed following the manufacturer's instructions. Resulting sequences were mapped to a reference genome with Bioscope and NovoalignCS software. Sequence variants were identified with SAMtools and filtered if present on dbSNP database. Initially a small set of de novo and somatic mutations were selected to be validated by sanger sequencing. Results: From 84 unknown de novo alterations, we selected 11 for validation according to the following criteria: all loss of function variants (1 splice site and 2 nonsenses; 8 missense variants that were classified as pathogenic in the prediction programs SIFT and/or Polyphen2 and were not at highly repetitive or homologous regions of the genome. From these 11 candidates, only one was confirmed to be a de novo mutation, while the remaining ten were either false positive or inherited variants. Regarding somatic alterations, 8 candidate mutations were identified and selected for validation. After sanger sequencing, only one was validated as a somatic mutation, one variant was also present in patient's blood and 6 alterations were not confirmed in the tumor, suggesting it to be sequencing artifacts. The gene affected by the validated somatic mutation encodes an important protein involved in RNA regulation and cell differentiation, and was not described to be mutated in any tumor type until now. Remarkably, this somatic mutation affects a highly conserved amino acid of this gene and this residue is a known binding site for a magnesium cofactor that is essential for the protein activity. The presence of this mutation was further evaluated in a cohort of 97 Wilms tumor samples and found to be present in 10% of cases. Preliminary functional studies of HEK293 cells transfected with an expression vector of this mutation demonstrated an impaired activity of the mutated protein. Conclusion: In this study we were able to identify one de novo and one somatic novel mutations in Wilms tumor. Initial results from our group suggest that this somatic mutation represents a driver and frequent event in this type of tumor. Citation Format: Giovana T. Torrezan, Elisa N. Ferreira, Mayra T M Castro, Adriana M. Nakahata, Pedro A. Galante, Daniel T. Ohara, Bruna D. Barros, Mariana Maschietto, Isabela W. Cunha, Cecilia M L Costa, Beatriz D. Camargo, Dirce M. Carraro. Identification of somatic and de novo mutations by exome sequencing in sporadic Wilms tumor. [abstract]. In: Proceedings of the AACR Special Conference on Pediatric Cancer at the Crossroads: Translating Discovery into Improved Outcomes; Nov 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;74(20 Suppl):Abstract nr A29.

Introduction: DNA repair genes are involved with repair of single strand breaks as well as double strand breaks which ultimately maintain the genome integrity. The genes involved with DNA repair are frequently deregulated in cancer and these defects can be exploited therapeutically. Our study aims to explore somatic and germline changes in DNA repair genes across multiple cancer types. Methods: Genomic profiling was performed on 226 tumor samples from 24 cancer types with ages ranging 19-82 years. We performed targeted exome sequencing of 562 genes in tumor and paired normal DNA which included 112 genes associated with cancer predisposition syndromes. In addition to identifying genomic changes in 33 key DNA repair genes (ATM, ATR, ARID1A, BAP1, BARD1, BRCA1, BRCA2, BRIP1, CDK12, CHEK1, CHEK2, ERCC2, ERCC3, ERCC4, FANCA gene family, MMR genes, NBS1, PALB2, PTEN, RAD50, RAD51, TP53 and POLE), we also characterized germline mutations using public databases (ClinVar, Ensembl). Results: Profiled specimens included breast cancer (17.5%), ovarian cancer (15%), CRC (11%), NSCLC (10%), uterine (6%), sarcoma (6%) and other cancers. The most commonly deleted or mutated (somatic) DNA repair genes included TP53 (55%), PTEN (16%), ARID1A (13%), FANCA (11%), ERCC2 (10%), and ATM, BAP1, CDK12, CHEK2 at 6% each and BRCA1/2 combined at (9%). Deleterious mutations in MMR genes were noted in 3.5% (8/226) which included 1 case of germline PMS2-S46I mutation. Interestingly, a 55 yr old male African American CRC patient harbored germline XPC-P334H mutation along with somatic MLH1-Y548fs. No mutations were found in FANCC, FANCF, FANCG and RAD51. Germline analysis revealed a total of 47 pathogenic and presumed pathogenic variants out of which 61.7%(29/47) were DNA repair genes. A total of 13% (30/226) of cases harbored germline variants in DNA repair genes. Germline events included 9 cases with BRCA1 and BRCA2 clinically significant mutations. Presence of loss of heterozygosity (LOH) at the BRCA locus in 5/9 cases and somatic mutations in 3/9 cases were noted in germline BRCA mutated samples. Germline and somatic BRCA1 and BRCA2 alterations were present in 10% (22/226) of total cohort and as expected, the majority were present in breast and epithelial ovarian cancer. Genetic deficiencies in DNA repair pathway genes are being exploited therapeutically with PARP inhibitors as well as DNA damaging chemotherapeutics. Conclusions: Exome sequencing identified subsets of patients with loss of function events in DNA repair genes that may be associated with benefit from PARP inhibitors and platinum agents. Somatic and germline biomarker testing revealed occurrence of BRCA1/2 as well as other DNA repair gene alterations across multiple cancers. It is imperative to explore the DNA repair pathway beyond BRCA1 and BRCA2 in patient selection for PARP inhibitors and DNA damaging agents and further investigation of this pathway is warranted in ongoing clinical trials. Citation Format: Gargi D. Basu, Tracey White, Janine LoBello, Ahmet Kurdoglu, Jeffrey Trent, Sen Peng, Matthew Halbert, Thomas Royce. Assessing germline and somatic alterations in DNA repair pathway in cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2779. doi:10.1158/1538-7445.AM2017-2779

e15016 Background: Treatment of pediatric solid tumors shows limited improvement even with intensification of conventional chemotherapy, suggesting novel approaches such as targeted therapies are needed. Trastuzumab Deruxtecan (T-DXd), a HER2-targeting antibody–drug conjugate, exhibits significant anti-cancer activity in breast cancers with a broad range of HER2 expression. T-DXd might be a promising agent for refractory or relapsed pediatric solid tumors, but its efficacy in pediatric tumors needs to be studied. Methods: Anti-cancer efficacy of T-DXd and its payload DXd were assessed in vitro by utilizing our in-house cancer cell line models. Cytotoxicity assays were performed for 60 pediatric cancer cell lines, including Neuroblastoma (NB) = 25, Ewing sarcoma / Ewing sarcoma family of tumors (EWS / EWSFT) = 17, Rhabdomyosarcoma (RMS) = 10, Others (Osteosarcoma, Brain tumor, Wilms tumor, Hepatoblastoma, and Malignant rhabdoid tumor (MRT) = 8, and 2 breast cancer cell lines expressing HER2 high or low (IHC score 2+ or 0) as positive or low control, respectively. We analyzed HER2 expression on the cell surface by flow cytometry and evaluated relative mean fluorescence intensity (MFI) values. Results: In the flow cytometric assessment, pediatric cancer cell lines showed smaller median MFI of 1.40 (0.67 - 2.71) compared with breast cancer control with HER2 high expression (33.77). The median MFI of each cell lines were 0.94 in NB, 1.76 in EWS / EWSFT, 1.42 in RMS, 1.52 in other pediatric cancers. Although low or no expression of HER2, certain inhibitory activities to the cell growth were observed for T-DXd against a part of NB, EWS, RMS and MRT cell lines, with the minimum IC50 values of 14.5 nM, 6.5 nM, 10.2 nM, 8.1 nM, respectively. In NB, EWS and RMS, a wide range of sensitivity to T-DXd were seen among different cell lines in the same disease. Most of cell lines showed high sensitivity to DXd (Median IC50 value: 0.90 nM [0.08 - 6.46 nM]), but, among them, cell lines with lower sensitivity to DXd tend to show less sensitivity to T-DXd. There was no clear correlation between sensitivity to T-DXd and HER2 expression among pediatric cancer cell lines, indicating that other mechanism such as intrinsic sensitivity to payload might affect antitumor activity of T-DXd. Conclusions: T-DXd exhibited antitumor efficacy against pediatric solid tumors in vitro irrespective of HER2 expression. Our results suggest that T-DXd might be an alternative therapy for pediatric solid tumor cases for whom conventional chemotherapies and other targeting therapies are ineffective. This study supports further investigation for T-DXd in this population.

To discover common and sub-type specific somatic alterations affecting key biological processes in pediatric cancers, we analyzed point mutations, copy number alterations, gene fusions and structural alterations detected from paired tumor-normal whole genome sequencing (n=655), whole exome sequencing (n=1,108), and RNA-seq data (n=913) of 1,705 leukemia and solid tumors. Our cohort consists of 693 B-lineage Acute Lymphoblastic Leukemia (B-ALL), 264 T-ALL, 211 Acute Myeloid Leukemia (AML), 318 Neuroblastoma (NBL), 128 Wilms Tumor (WT), and 91 Osteosarcoma (OS) with a median mutation rate of 0.28-0.58 per Mb. We identified 130 potential driver genes based on significance of variant recurrence and pathogenicity within each cancer type and across all cancer types. Seventy-two (55%) driver genes were significant in one cancer type, thirty eight were significant in > 1 leukemia subtype, thirteen (NRAS, WT1, MYCN, PTEN, TP53, KRAS, RB1, ATRX, PTPN11, MLLT1, BCOR, SETD2, NF1) were significant in both leukemia and solid tumor while the remaining seven (MGA, SF3B1, ASXL1, BCORL1, STAG2, ACTB, NIPBL) were significant only in pan-cancer analysis. The number of mutated driver genes per sample ranged from 0.8 in WT to 5.8 in T-ALL, lower when considering only point mutations (from 0.3 in NBL to 3.1 in T-ALL). The most frequently mutated biological processes affecting both leukemia and solid tumor were transcription factors (56% of samples), cell cycle (41%), epigenetic regulators (36%), Ras signaling (21%), PI-3K (11%), and the MYC complex (7%). By contrast, the JAK signaling pathway was mutated only in leukemia (16%) while mutations in the NOTCH signaling pathway were exclusive to T-ALL (77%). Aberrant transcription may also affect the normal function of a driver gene. For example, the RAS signaling pathway was mutated in B-ALL (35%), T-ALL (15%), AML (37%) and NBL (4.3%). Aside from the known KRAS 4a isoform found in all cancer types, we discovered two novel KRAS isoforms present in 71.1% of B-ALL, 67.9% of T-ALL, 71.3% of AML and 3.0% of NBL but not in WT or OS. Allele-specific expression (ASE) was detected in 205 (6.8%) of 3,016 expressed somatic mutations, and 97% (32 out of 33) of truncation mutations on autosomes exhibit reduced expression of the mutant allele likely due to nonsense mediated decay. Two ASE mutations, WT1 D447N in a cytogenetically normal AML and JAK2 D873N in a B-ALL, were selected for single-cell sequencing and successfully validated. Only 44% of our driver genes match those identified in adult cancer. This, coupled with our finding that point mutations only accounted for 48% of the driver alterations, may provide new insight into the design of precision treatment for pediatric cancer. Our presented data will be made public at NCI’s Genome Data Commons (gdc.cancer.gov) and can be explored on our ProteinPaint data portal (pecan.stjude.org). Citation Format: Xiaotu Ma, Yu Liu, Yanling Liu, Michael Edmonson, Charles Gawad, Xin Zhou, Yongjin Li, Michael Rusch, John Easton, Mark Wilkinson, Leandro C. Hermida, Sean Davis, Malcolm Smith, Jaime Guidry Auvil, Paul Meltzer, Ching C. Lau, Elizabeth Perlman, John M. Maris, Soheil Meshinchi, Stephen P. Hunger, Daniela S. Gerhard, Jinghui Zhang. Comparison of somatic alterations in the genome and transcriptome of 1,705 pediatric leukemia and solid tumors: a report from the Children’s Oncology Group (COG) - NCI TARGET Project [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3004. doi:10.1158/1538-7445.AM2017-3004

SummaryBackgroundWilms tumour is the most common childhood renal cancer and is genetically heterogeneous. While several Wilms tumour predisposition genes have been identified, there is strong evidence that further predisposition genes are likely to exist. Our study aim was to identify new predisposition genes for Wilms tumour.MethodsIn this exome sequencing study, we analysed lymphocyte DNA from 890 individuals with Wilms tumour, including 91 affected individuals from 49 familial Wilms tumour pedigrees. We used the protein-truncating variant prioritisation method to prioritise potential disease-associated genes for further assessment. We evaluated new predisposition genes in exome sequencing data that we generated in 334 individuals with 27 other childhood cancers and in exome data from The Cancer Genome Atlas obtained from 7632 individuals with 28 adult cancers.FindingsWe identified constitutional cancer-predisposing mutations in 33 individuals with childhood cancer. The three identified genes with the strongest signal in the protein-truncating variant prioritisation analyses were TRIM28, FBXW7, and NYNRIN. 21 of 33 individuals had a mutation in TRIM28; there was a strong parent-of-origin effect, with all ten inherited mutations being maternally transmitted (p=0·00098). We also found a strong association with the rare epithelial subtype of Wilms tumour, with 14 of 16 tumours being epithelial or epithelial predominant. There were no TRIM28 mutations in individuals with other childhood or adult cancers. We identified truncating FBXW7 mutations in four individuals with Wilms tumour and a de-novo non-synonymous FBXW7 mutation in a child with a rhabdoid tumour. Biallelic truncating mutations in NYNRIN were identified in three individuals with Wilms tumour, which is highly unlikely to have occurred by chance (p<0·0001). Finally, we identified two de-novo KDM3B mutations, supporting the role of KDM3B as a childhood cancer predisposition gene.InterpretationThe four new Wilms tumour predisposition genes identified—TRIM28, FBXW7, NYNRIN, and KDM3B—are involved in diverse biological processes and, together with the other 17 known Wilms tumour predisposition genes, account for about 10% of Wilms tumour cases. The overlap between these 21 constitutionally mutated predisposition genes and 20 genes somatically mutated in Wilms tumour is limited, consisting of only four genes. We recommend that all individuals with Wilms tumour should be offered genetic testing and particularly, those with epithelial Wilms tumour should be offered TRIM28 genetic testing. Only a third of the familial Wilms tumour clusters we analysed were attributable to known genes, indicating that further Wilms tumour predisposition factors await discovery.FundingWellcome Trust.

Simple SummaryTumors occurring at a young age are distinct from tumors in older individuals, clinically and pathologically. As small round blue cell tumors (SRBCTs), they often show a resemblance to stem cells and immature precursor cells during embryonal development. Recently, immunotherapy has become an option for a subset of patients with limited success. We observed that in almost all the pediatric SRBCT types investigated (n = 1134) there was an inverse relationship, when comparing genes highly expressed in stem cells with genes encoding MHC class I molecules. MHC class I molecules are important in tumor cell recognition by cytotoxic T cells. We suspect that these tumors are derived from multipotent precursor cells that naturally show a low MHC class I expression and a lack of immune recognition necessary for prenatal proliferation and development.Recently, immunotherapeutic approaches have become a feasible option for a subset of pediatric cancer patients. Low MHC class I expression hampers the use of immunotherapies relying on antigen presentation. A well-established stemness score (mRNAsi) was determined using the bulk transcriptomes of 1134 pediatric small round blue cell tumors. Interestingly, MHC class I gene expression (HLA-A/-B/-C) was correlated negatively with mRNAsi throughout all diagnostic entities: neuroblastomas (NB) (n = 88, r = −0.41, p < 0.001), the Ewing’s sarcoma family of tumors (ESFT) (n = 117, r = −0.46, p < 0.001), rhabdomyosarcomas (RMS) (n = 158, r = −0.5, p < 0.001), Wilms tumors (WT) (n = 224, r = −0.39, p < 0.001), and central nervous system-primitive neuroectodermal tumors CNS-PNET (r = −0.49, p < 0.001), with the exception of medulloblastoma (MB) (n = 76, r = −0.24, p = 0.06). The negative correlation of MHC class I and mRNAsi was independent of clinical features in NB, RMS, and WT. In NB and WT, increased MHC class I was correlated negatively with tumor stage. RMS patients with a high expression of MHC class I and abundant CD8 T cells showed a prolonged overall survival (n = 148, p = 0.004). Possibly, low MHC class I expression and stemness in pediatric tumors are remnants of prenatal tumorigenesis from multipotent precursor cells. Further studies are needed to assess the usefulness of stemness and MHC class I as predictive markers.

Most pediatric malignancies require some form of cross-sectional imaging, either for staging or response assessment. The majority of these are solid tumors and this review addresses the role of MRI, as well as other cross-sectional and functional imaging techniques, for evaluating the most common pediatric solid tumors. The primary emphasis is on neuroblastoma, hepatoblastoma and Wilms tumor, three of the most common non-central-nervous-system (CNS) pediatric solid tumors encountered in young children. The initial focus will be a review of the imaging techniques and approaches used for diagnosis, staging and early post-treatment response assessment, followed by a discussion of the role surveillance imaging plays in pediatric oncology and a brief review of other emerging imaging techniques. The lessons learned here can be applied to most other pediatric tumors, including rhabdomyosarcoma, Ewing sarcoma and osteosarcoma, as well as germ cell tumors, neurofibromatosis and other rare tumors. Although lymphoma, in particular Hodgkin lymphoma, represents one of the more common pediatric malignancies, this is not discussed in detail here. Rather, many of the lessons that we have learned from lymphoma, specifically with regard to how we integrate both anatomical imaging and functional imaging techniques, is applied to the discussion of the other pediatric solid tumors.

BackgroundSeveral studies have shown significant variation in overall survival rates from childhood cancer between countries, using population-based cancer registry (PBCR) data for all cancers combined and for many individual tumour types among children. Without accurate and comparable data on Tumour stage at diagnosis, it is difficult to define the reasons for these survival differences. This is because measurement systems designed for adult cancers do not apply to children’s cancers and cancer registries often hold limited information on paediatric tumour stage and the data sources used to define it.AimsThe BENCHISTA project aims to test the application of the international consensus “Toronto Staging Guidelines” (TG) for paediatric tumours by European and non-European PBCRs for six common paediatric solid tumours so that reliable comparisons of stage at diagnosis and survival rates by stage can be made to understand any differences. A secondary aim is to test the data availability and completeness of collection of several ‘Toronto’ consensus non-stage prognostic factors, treatment types given, occurrence of relapse/progression and cause of death as a descriptive feasibility study.MethodsPBCRs will use their permitted data access channels to apply the Toronto staging guidelines to all incident cases of six solid childhood cancers (medulloblastoma, osteosarcoma, Ewings sarcoma, rhabdomyosarcoma, neuroblastoma and Wilms tumour) diagnosed in a consecutive three-year period within 2014–2017 in their population. Each registry will provide a de-identified patient-level dataset including tumour stage at diagnosis, with only the contributing registry holding the information that would be needed to re-identify the patients. Where available to the registry, patient-level data on ‘Toronto’ non-stage prognostic factors, treatments given and clinical outcomes (relapse/progression/cause of death) will be included. More than 60 PBCRs have been involved in defining the patient-level dataset items and intend to participate by contributing their population-level data. Tumour-specific on-line training workshops with clinical experts are available to cancer registry staff to assist them in applying the Toronto staging guidelines in a consistent manner. There is also a project-specific help desk for discussion of difficult cases and promotion of the CanStaging online tools, developed through the International Association of Cancer Registries, to further ensure standardisation of data collection. Country-specific stage distribution and observed survival by stage at diagnosis will be calculated for each tumour type to compare survival between countries or large geographical regions.DiscussionThis study will be promote and enhance the collection of standardized staging data for childhood cancer by European and non-European population-based cancer registries. Therefore, this project can be seen as a feasibility project of widespread use of Toronto Staging at a population-level by cancer registries, specifying the data sources used and testing how well standardized the processes can be. Variation in tumour stage distribution could be due to real differences, to different diagnostic practices between countries and/or to variability in how cancer registries assign Toronto stage. This work also aims to strengthen working relationships between cancer registries, clinical services and cancer-specific clinical study groups, which is important for improving patient outcomes and stimulating research.

Background: Advances in sequencing technologies allow for provision of genome-scale data to physicians caring for pediatric cancer patients but current experience with the clinical application of genomic sequencing is limited and the diagnostic yield of these methods is unclear. Methods: The goal of the BASIC3 (Baylor Advancing Sequencing into Childhood Cancer Care) study is to determine the clinical impact of incorporating tumor and constitutional whole exome sequencing (WES) into the care of children with newly diagnosed solid tumors at Texas Children's Cancer Center (target enrollment n=280). WES of patient blood and frozen tumor samples is being conducted in the CLIA-certified Whole Genome Laboratory at Baylor College of Medicine using the VCRome 2.1 capture reagent and Illumina paired-end sequencing with reports incorporated in the medical record. Results: 120 patients have enrolled to date, including 39 (33%) and 81 (67%) with CNS and non-CNS tumors, respectively. Despite limited diagnostic biopsies in many patients, tumor samples adequate for WES have been obtained from 97 subjects (81%). WES results have been reported for 89 patients. Tumor WES (n=73) revealed 20 of 73 tumors (27%) to contain mutations classified as having proven or potential clinical utility, including recurrent alterations of CTNNB1, BRAF, KIT, and NRAS/KRAS. Notably, less than 50% of somatic mutations would have been detected on an adult-focused cancer panel, BCM Cancer Gene Mutation Panel v.2. Germline WES (n=89) identified diagnostic findings in 11 cases (12%) including 8 patients with pathogenic mutations in dominant cancer susceptibility genes (singletons except for 2 patients with TP53 mutations). Four of these 8 patients had genetic testing recommended clinically. There were 2 patients with mutations providing the genetic cause of non-cancer medical problems and 1 patient with a mutation which explained both liver disease and hepatocellular carcinoma. Downstream testing of at-risk relatives has occurred rapidly in several families and cancer screening recommendations implemented. Seven (8%) medically actionable incidental findings unrelated to phenotype were reported, predominantly in cardiovascular genes and mitochondrial DNA. Conclusions: These data demonstrate the feasibility of routine WES in the pediatric oncology setting. Early results demonstrate that clinically relevant findings are identified by tumor and germline WES in 38% of pediatric solid tumor patients. The yield of clinically relevant somatic and germline alterations would likely increase further by incorporation of complementary genomic methods (e.g. RNA-seq or copy number analysis). Assessment of the clinical utility of the tumor and germline exomes and preferences for reporting of these results to physicians and parents are under study. Supported by NHGRI/NCI 1U01HG006485. Citation Format: Donald W. Parsons, Angshumoy Roy, Federico A. Monzon, Yaping Yang, Dolores H. López-Terrada, Murali M. Chintagumpala, Stacey L. Berg, Susan G. Hilsenbeck, Tao Wang, Robin A. Kerstein, Sarah Scollon, Katie Bergstrom, Richard L. Street, Laurence B. McCullough, Amy L. McGuire, Uma Ramamurthy, Jeff G. Reid, Donna M. Muzny, David A. Wheeler, Christine M. Eng, Richard A. Gibbs, Sharon E. Plon. Diagnostic yield of clinical tumor and germline exome sequencing for newly diagnosed children with solid tumors. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5169. doi:10.1158/1538-7445.AM2014-5169

Diagnosis and Classification of the Small Round-Cell Tumors of Childhood

8539 Background: ESFT comprise approximately 2% of malignancies in childhood. Although there are scattered reports in the literature of ESFT as a SMN, the proportion of SMN that are ESFT is unknown. Methods: We reviewed our institutional experience from 3/62 to 12/03 with ESFT arising as a SMN. Demographic data, diagnostic and treatment information for both the PMN and SMN, and outcome data were recorded. Results: Of the 431 patients with 2 or more malignancies, 8 (1.9%) had ESFT as a SMN. The median age at diagnosis of PMN was 4.2 years (range, 0.8–12.5 years), and of ESFT was 13.4 years (range, 4.9–22.0 years). Five patients were female and 7 were white. The PMN was retinoblastoma (n=3), Wilms tumor (n=2), acute lymphoblastic leukemia, Hodgkin lymphoma, and non-Hodgkin lymphoma (n=1 each). Six patients received chemotherapy for treatment of the PMN including alkylating agents (n=3), anthracyclines (n=6), and etoposide (n=1). Four also received radiotherapy (RT) for the PMN (dose range, 10.8–48 Gy, median 30 Gy). The median latency between the PMN and ESFT was 6.3 years (range, 3.1–18.3 years). The ESFT primary sites were chest wall/rib (n=4), extremity (n=3) and pelvis (n=1). Three patients had metastases at presentation. Among the 4 patients who had received RT previously, 2 ESFT arose outside the field and 2 arose at the field margins. Four patients have died: 3 due to progressive ESFT and 1 due to a third malignancy (osteosarcoma arising within the RT field used to treat the ESFT). The 5-year estimated survival following the development of ESFT was 57.1%±16.7%. Conclusions: The proportion of ESFT as a SMN following treatment of childhood cancer is similar to the proportion of ESFT as a PMN in childhood. Patients with retinoblastoma may be at higher risk than other childhood cancer survivors for secondary ESFT. Most secondary ESFT are not radiation-induced. Survival appears to be only slightly inferior to that of de novo ESFT. No significant financial relationships to disclose.

Unlike osteosarcoma, the Ewing sarcoma family of tumors (ESFT) has rarely been reported as secondary malignant neoplasms after treatment of childhood cancer. ESFT arising as a second cancer was reviewed and characterized at our childhood cancer center. A retrospective review was undertaken of 11,183 patients age <21 years who were treated for a primary cancer between March 1962 and December 2003 at St. Jude Children's Research Hospital. All cases of ESFT were confirmed to have a rearranged EWS gene. Six cases of ESFT (1.3% of 479 second cancers) were identified in patients previously treated for lymphoma (n = 3), leukemia (n = 1), retinoblastoma (n = 1), or Wilms tumor (n = 1). None of these patients had a family history suggestive of a familial cancer syndrome. The median time between diagnosis of primary cancer and diagnosis of ESFT was 5.9 years (range, 3.1-18.3 years). ESFT occurred in typical anatomic locations: rib (n = 2), chest wall soft tissues (n = 2), pelvis (n = 1), and extremity (n = 1). One tumor arose at the margin of a previous radiotherapy field and 1 arose distant from previous radiotherapy fields; all other patients had not received radiotherapy. Three patients are alive at the time of this report, including 2 whose ESFT was diagnosed more than 8 years ago. ESFT occurs rarely after treatment of a primary cancer during childhood, and most cases do not appear to be related to radiation therapy. Long-term survival can be achieved in some patients, and therefore secondary ESFT should be treated with curative intent.

Background Accurate oncological diagnoses are essential to provide personalized and optimum care for patients. In children, renal tumors account for approximately one in 20 malignancies. Diagnostic workup in pediatric renal tumors is current focused on epidemiology, radiology, and histology, with a very limited role for molecular analysis outside of suspected cancer predisposition. Methods Retrospective clinical record review of seven pediatric and young adult renal tumor patients presenting to a single principal treatment center in the East of England, UK. Data collection was focused on their clinical presentation, radiology, histopathology, and molecular investigations including whole genome sequencing (WGS), treatment and outcomes. We analyzed the impact of molecular analysis on the care of these patients. Results Four patients presented with histologically difficult to classify renal tumors. Subsequent nephrectomy provided no additional information over biopsy in the two cases where a biopsy was performed first. Two young patients with histological concerns over renal cell carcinoma (RCC) had somatic mutations reported in Wilms tumor (WT) and responded well to WT treatment. One patient had histologically mixed features of papillary RCC and epithelial WT. WGS revealed a copy number profile consistent with papillary RCC as well as somatic WT changes and responded well and durably to chemo/radiotherapy, not expected for RCC alone. A young adult with an atypical RCC was shown to harbor a ERC1::CCNY fusion likely defining a novel entity. A further three cases, who did not have classical features of WT/cancer predisposition, were found to harbor mosaic/germline predisposition variants; allowing for appropriate treatment as per syndromic WT protocols. Discussion Diagnostic uncertainty is a challenge for oncologists, their patients, and families. Here we provide evidence that agnostic molecular analysis, including whole genomic sequencing (WGS), can be helpful in delineating such cases. In two children the molecular analysis helped to define the diagnosis as WT despite histological concerns for RCC. A novel tumor with mixed WT/RCC phenotype and genotype was responsive to chemo/radiotherapy. Molecular analysis thus improves the accuracy of diagnosis and helps to define novel entities. WT is well recognized to occur in the context of cancer predisposition syndromes. At present, genetics referrals and investigations are limited to those with suggestive family history or clinical features. Routinely undertaking molecular analysis will increase the rate of detection of underlying predisposition. We propose rapid turn-around molecular analysis for those undergoing pre-operative chemotherapy (as practiced in Europe) to identify patients and to plan for nephron-sparing surgery to reduce the risk of long-term renal replacement therapy. The molecular multidisciplinary team is crucial for the interpretation of routinely performed agnostic molecular analysis in children and young people with renal tumors given the evolving complexity of such cases. Citation Format: Sarah M. Leiter, Aisosa Guobadia, Ben Fleming, Thankamma Ajithkumar, James Armitage, Ruth Armstrong, GA Amos Burke, Charlotte Burns, Tanzina Chowdhury, Nicholas Coleman, Helen Hatcher, Gail Horan, Lisa Howell, Anna-May Long, Sarah McDonald, Thomas J. Mitchell, James C. Nicholson, Thomas Roberts, Grant D. Stewart, John A. Tadross, Patrick Tarpey, Claire Trayers, Jamie Trotman, James Watkins, Anne Y. Warren, Godran Vujanic, C. Elizabeth Hook, Sam Behjati, Matthew J. Murray. Molecular analysis improves the diagnosis of young people with renal tumors [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pediatric Cancer Research; 2024 Sep 5-8; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl):Abstract nr A011.