Lynch Syndrome-associated Cancers Research Articles

Lynch Syndrome-associated Genomic Variants.

Lynch Syndrome, a hereditary disorder characterized by germline mutations in mismatch repair (MMR) genes, is a major contributor to colorectal cancers. It has also been identified in endometrial cancer. Despite the established role of MMR deficiency in tumorigenesis, the specific genomic alterations driving Lynch syndrome-associated endometrial cancer, and their overlap with colorectal cancer, remain incompletely understood. This study aims to fill this gap by performing a detailed comparative analysis of germline and somatic mutations in endometrial cancer within the context of Lynch syndrome. We conducted whole exome sequencing on matched germline and somatic DNA from 13 patients diagnosed with Lynch syndrome-associated endometrial cancer. High-depth sequencing was performed, followed by rigorous bioinformatics analysis to identify and annotate variants, focusing on their potential pathogenicity and relevance to both endometrial and colorectal cancer. Our analysis revealed 1,118 germline and 14,051 somatic variants, with 493 variants common to both. Recurrent pathogenic mutations in MLH1, MSH2, and MSH6 were confirmed, highlighting their critical role in Lynch syndrome. Notably, frequent somatic mutations in the PIK3CA and PTEN genes were identified, implicating the PI3K/AKT/mTOR pathway as a key oncogenic driver in these cancers. Additionally, novel somatic mutations in genes related to the extracellular matrix such as FBN1 and SPARC were uncovered, suggesting a possible unique role in endometrial tumor progression. This study provides new insights into the molecular basis of Lynch syndrome-associated endometrial cancer, emphasizing the overlap in oncogenic pathways with colorectal cancer. The discovery of shared and unique genetic mutations highlights the importance of developing combined treatment strategies and suggests that targeting these specific mutations could improve therapy for patients with Lynch syndrome-associated cancers.

Lynch syndrome screening in patients with young-onset extra-colorectal Lynch syndrome-associated cancers.

Lynch syndrome (LS) is a hereditary cancer syndrome caused by pathogenic germline variants in mismatch repair (MMR) genes, which predisposes to various types of cancers showing deficient MMR (dMMR). Identification of LS probands is crucial to reduce cancer-related deaths in affected families. Although universal screening is recommended for colorectal and endometrial cancers, and age-restricted screening is proposed as an alternative, LS screening covering a broader spectrum of cancer types is needed. In the current study, we elucidated the rate of dMMR tumors and evaluated the outcome of LS screening in young-onset extra-colorectal LS-associated cancers. Immunohistochemistry for MMR proteins were retrospectively performed in a total of 309 tissue samples of endometrial, non-mucinous ovarian, gastric, urothelial, pancreatic, biliary tract, and adrenal cancers in patients < 50years of age. Clinicopathological information and the results of genetic testing were obtained from medical charts. There were 24 dMMR tumors (7.8%) including 18 endometrial, three ovarian, two urothelial, and one gastric cancer. Co-occurrence of colorectal cancer and family history of LS-associated cancers was significantly enriched in patients with dMMR tumors. Among the 16 patients with dMMR tumors who were informed of the immunohistochemistry results, five with endometrial and one with urothelial cancer were diagnosed as LS with positive pathogenic variants in MMR genes. We report the outcome of immunohistochemistry for MMR proteins performed in multiple types of young-onset extra-colorectal LS-associated cancers. Our study demonstrates the feasibility of a comprehensive LS screening program incorporating young-onset patients with various types of extra-colorectal LS-associated cancers.

Lynch syndrome-associated and sporadic microsatellite unstable colorectal cancers: different patterns of clonal evolution yield highly similar tumours.

Microsatellite unstable colorectal cancer (MSI-CRC) can arise through germline mutations in mismatch repair (MMR) genes in individuals with Lynch syndrome (LS), or sporadically through promoter methylation of the MMR gene MLH1. Despite the different origins of hereditary and sporadic MSI tumours, their genomic features have not been extensively compared. A prominent feature of MMR-deficient genomes is the occurrence of many indels in short repeat sequences, an understudied mutation type due to the technical challenges of variant calling in these regions. In this study, we performed whole genome sequencing and RNA-sequencing on 29 sporadic and 14 hereditary MSI-CRCs. We compared the tumour groups by analysing genome-wide mutation densities, microsatellite repeat indels, recurrent protein-coding variants, signatures of single base, doublet base, and indel mutations, and changes in gene expression. We show that the mutational landscapes of hereditary and sporadic MSI-CRCs, including mutational signatures and mutation densities genome-wide and in microsatellites, are highly similar. Only a low number of differentially expressed genes were found, enriched to interferon-γ regulated immune response pathways. Analysis of the variance in allelic fractions of somatic variants in each tumour group revealed higher clonal heterogeneity in sporadic MSI-CRCs. Our results suggest that the differing molecular origins of MMR deficiency in hereditary and sporadic MSI-CRCs do not result in substantial differences in the mutational landscapes of these tumours. The divergent patterns of clonal evolution between the tumour groups may have clinical implications, as high clonal heterogeneity has been associated with decreased tumour immunosurveillance and reduced responsiveness to immunotherapy.

A metabolic-inflammatory-nutritional score (MINS) is associated with lymph node metastasis and prognostic stratification for endometrial cancer patients.

Objective: This study aims to propose a personalized cancer prediction model based on the metabolic-inflammatory-nutritional score (MINS) for predicting lymph node metastasis (LNM) in endometrial cancer (EC) and validated prediction of survival probability in patients with a family history of Lynch syndrome-associated cancers (LSAC). Methods: A total of 676 patients diagnosed with EC were enrolled in this study. We calculated the optimal cutoff value using restricted cubic splines (RCS) analysis or the mean value. Our feature selection process for constructing the MINS involved using the LASSO regression model. MINS were evaluated for LNM using logistic regression analysis. To assess the prognostic value of the MINS, we generated survival curves using the Kaplan-Meier method with a log-rank test. Furthermore, we constructed a nomogram to validate the prognostic significance of the MINS. The predictive accuracy of nomogram was evaluated using the concordance index (C-index) and calibration plot. Results: LNM risk was associated with family history of LSAC and MINS group (all adjusted p<0.05). Patients in the high-risk MINS group or patients with a family history of LSAC exhibited poorer overall survival (p=0.038, p=0.001, respectively). Additionally, a nomogram was demonstrated effective predictive performance with a C-index of 0.778 (95% CI: 0.725-0.832). Conclusion: Preoperative MINS has been determined to be associated with the risk of LNM in EC patients. Utilizing MINS as a basis, the development of a prognostic nomogram holds promise as an effective tool for risk stratification in clinical settings among EC patients with a family history of LSAC.

The prevalence of lynch syndrome (DNA mismatch repair protein deficiency) in patients with primary localized prostate cancer using immunohistochemistry screening

BackgroundProstate cancer is one of the most heritable human cancers. Lynch syndrome is an autosomal dominant inheritance caused by germline mutations in DNA mismatch repair (MMR) genes, which are also associated with an increased incidence of prostate cancer. However, prostate cancer has not been defined as a Lynch syndrome-associated cancer. The proportion of Lynch syndrome patients in primary prostate cancers is unclear. In this study, we investigated MMR protein loss using universal immunohistochemical screening to determine the prevalence of Lynch syndrome in patients with localized prostate cancer who underwent radical prostatectomy.MethodsOne hundred twenty-nine surgical specimens from radical prostatectomy performed at Toranomon Hospital between 2012 and 2015 were retrospectively tested using universal screening with immunohistochemistry staining for expression of the MMR proteins MLH1, PMS2, MSH2, and MSH6. For all suspected MMR-deficient patients, germline genetic tests focusing on MMR genes were performed.ResultsMMR protein loss was found in only one patient (0.8%) who showed dual MSH2/MSH6 loss. This patient showed a single nucleotide pathogenic germline mutation from c.1129 C to T (p.Gln377*) at exon 7 in the MSH2 gene. He was diagnosed with a primary prostate cancer at 66 years of age. He had a documented history of Lynch syndrome (Muir–Torre syndrome) with previous colon cancer, sebaceous tumor, and keratoacanthoma as well as subsequent bladder cancer, all of which also showed dual MSH2/MSH6 loss. He also had a strong family history of colorectal and other Lynch syndrome-associated cancers. The pathological stage was pT3aN0M0, and the pathological grade was Gleason 7(4 + 3) with tertiary pattern 5.ConclusionsIn this study, immunohistochemical screening of MMR proteins for Lynch syndrome was performed in a series of prostate cancer cases. The prevalence of Lynch syndrome in localized prostate cancer was 0.8%, which is low compared with other Lynch syndrome-associated cancers.

Mismatch repair deficiency testing in Lynch syndrome-associated urothelial tumors.

Lynch syndrome-associated cancer develops due to germline pathogenic variants in one of the mismatch repair (MMR) genes, MLH1, MSH2, MSH6 or PMS2. Somatic second hits in tumors cause MMR deficiency, testing for which is used to screen for Lynch syndrome in colorectal cancer and to guide selection for immunotherapy. Both MMR protein immunohistochemistry and microsatellite instability (MSI) analysis can be used. However, concordance between methods can vary for different tumor types. Therefore, we aimed to compare methods of MMR deficiency testing in Lynch syndrome-associated urothelial cancers. Ninety-seven urothelial (61 upper tract and 28 bladder) tumors diagnosed from 1980 to 2017 in carriers of Lynch syndrome-associated pathogenic MMR variants and their first-degree relatives (FDR) were analyzed by MMR protein immunohistochemistry, the MSI Analysis System v1.2 (Promega), and an amplicon sequencing-based MSI assay. Two sets of MSI markers were used in sequencing-based MSI analysis: a panel of 24 and 54 markers developed for colorectal cancer and blood MSI analysis, respectively. Among the 97 urothelial tumors, 86 (88.7%) showed immunohistochemical MMR loss and 68 were successfully analyzed by the Promega MSI assay, of which 48 (70.6%) were MSI-high and 20 (29.4%) were MSI-low/microsatellite stable. Seventy-two samples had sufficient DNA for the sequencing-based MSI assay, of which 55 (76.4%) and 61 (84.7%) scored as MSI-high using the 24-marker and 54-marker panels, respectively. The concordance between the MSI assays and immunohistochemistry was 70.6% (p = 0.003), 87.5% (p = 0.039), and 90.3% (p = 1.00) for the Promega assay, the 24-marker assay, and the 54-marker assay, respectively. Of the 11 tumors with retained MMR protein expression, four were MSI-low/MSI-high or MSI-high by the Promega assay or one of the sequencing-based assays. Our results show that Lynch syndrome-associated urothelial cancers frequently had loss of MMR protein expression. The Promega MSI assay was significantly less sensitive, but the 54-marker sequencing-based MSI analysis showed no significant difference compared to immunohistochemistry. Data from this study alongside previous studies, suggest that universal MMR deficiency testing of newly diagnosed urothelial cancers, using immunohistochemistry and/or sequencing-based MSI analysis of sensitive markers, offer a potentially useful approach to identification of Lynch syndrome cases.

Pediatric manifestations of Lynch Syndrome: A single center experience

Lynch syndrome is an autosomal dominant condition caused by a heterozygous variation in one of the DNA mismatch repair (MMR) genes that pre-disposes individuals to early onset colorectal cancers and other malignancies. Lynch syndrome is generally considered an adult-onset disorder, with malignancy rarely manifesting in childhood. Colorectal cancer is extremely rare in children, but hereditary syndromes including Lynch syndrome are an important cause. We aimed to assess the frequency and clinical course of children with Lynch syndrome associated pediatric colorectal cancers at our institution over the last 20 years. In this retrospective study, we describe four cases of children with Lynch syndrome-associated colorectal cancers age 14-17 years at diagnosis. All patients were diagnosed with Lynch syndrome after diagnosis, despite three of them having family histories consistent with Lynch syndrome. This series highlights a rare but important cause of pediatric malignancy and points to the need for early education on colorectal cancer warning symptoms and open discussion about this condition in affected families. It also illustrates the need for a thorough family history and a high level of suspicion for Lynch syndrome in children based on family background, as early detection may be key to improving cancer outcomes.

5MO CDK4/6 blockade is as effective as immune-checkpoint inhibition in tumor growth control of Mlh1-/- and Msh2loxP/loxP villin-Cre mice

Mismatch-repair deficiency (dMMR) is a hallmark of Lynch syndrome-associated cancers, often resulting from inactivating mutations in MLH1 or MSH2. These tumors have a high likelihood of responding to immune checkpoint inhibitors (ICI). Still, intrinsic or acquired resistance mechanisms impair patients’ outcomes. Here, we compared the therapeutic potential of an anti-PD-L1 inhibitor with the CDK4/6 inhibitor abemaciclib in two preclinical mouse models of dMMR-driven carcinogenesis.

Clinicopathological characterization of a real-world multicenter cohort of endometrioid ovarian carcinoma: Analysis of the French national ESME-Unicancer database

BackgroundPrognostic significance of endometrioid epithelial ovarian cancer (EOC) is controversial. We compared clinical, pathological, and biological features of patients with endometrioid and serous EOC, and assessed the independent effect of histology on outcomes. MethodsWe conducted a multicenter retrospective analysis of patients with EOC selected from the French Epidemiological Strategy and Medical Economics OC database between 2011 and 2016. Our main objective was to compare overall survival (OS) in endometrioid and serous tumors of all grades. Our second objectives were progression-free survival (PFS) and prognostic features. ResultsOut of 10,263 patients included, 3180 cases with a confirmed diagnosis of serous (N = 2854) or endometrioid (N = 326) EOC were selected. Patients with endometrioid histology were younger, more often diagnosed at an early stage, with lower-grade tumors, more frequently dMMR/MSI-high, and presented more personal/familial histories of Lynch syndrome-associated cancers. BRCA1/2 mutations were more frequently identified in the serous population. Endometrioid patients were less likely to receive chemotherapy, with less bevacizumab. After median follow-up of 51.7 months (95CI[50.1–53.6]), five-year OS rate was 81% (95CI[74–85]) in the endometrioid subgroup vs. 55% (95CI[53–57] in the serous subset (p < 0.001, log-rank test). In multivariate analyses including [age, ECOG-PS, FIGO, grade, and histology], the endometrioid subtype was independently associated with better OS (HR = 0.38, 95CI[0.20–0.70], p= 0.002) and PFS (HR = 0.53, 95CI[0.37–0.75], p < 0.001). ConclusionsClinicopathological features at diagnosis are not the same for endometrioid and serous EOC. Endometrioid histology is an independent prognosis factor in EOC. These observations suggest the endometrioid population requires dedicated clinical trials and management.

Lynch syndrome-associated epithelial ovarian cancer and its immunological profile

IntroductionLynch syndrome is a multi-tumor syndrome characterized by mismatch repair deficiency (MMR-d), microsatellite instability (MSI), and increased tumor-infiltrating lymphocytes (TILs) making these tumors candidates for treatment with immune checkpoint inhibitors. However, response may depend on tumor-induced immune evasion mechanisms, e.g. loss of Beta-2-Microglobulin (B2M) or upregulation of programmed death protein ligand 1 (PD-L1). We investigated the immune response and B2M and PD-L1 expression in Lynch syndrome-associated ovarian cancers. MethodsWe successfully analyzed 30 Lynch syndrome-associated epithelial ovarian cancers collected through the Danish Hereditary Non-Polyposis Colorectal Cancer (HNPCC) register. MMR-d, MSI, immune response (CD3, CD8, and CD68), and immune evasion mechanisms (B2M and PD-L1) were investigated. Statistical associations between these markers were evaluated in addition to survival in relation to B2M/PD-L1. ResultsOf the 29 evaluable tumors, 27 were MMR-d (93.1%). Likewise of 26 evaluable tumors, 14 were MSI (53.8%). MMR-d/MMR-proficiency associated with MSI/MSS in 60.0%. Half of the ovarian tumors presented with high levels of TILs. Loss of B2M expression was observed in 46.7% of the tumors, while expression of PD-L1 was seen in 28.0% of the cases. There was no association between B2M/PD-L1 and MSI/TILs/survival. Loss of B2M was often seen in tumors with low TILs (p = 0.056 or p = 0.059 for CD3 and CD8 positive cells, respectively). ConclusionMMR-d, MSI, and TILs are also seen in Lynch syndrome-associated ovarian cancers making these potential candidates for checkpoint-based immunotherapy. The clinical impact from immune evasion through loss of B2M needs to be investigated further in larger cohorts.

The diverse molecular profiles of lynch syndrome-associated colorectal cancers are (highly) dependent on underlying germline mismatch repair mutations.

Lynch syndrome (LS) is a hereditary cancer syndrome that accounts for 3% of all new colorectal cancer (CRC) cases. Patients carry a germline pathogenic variant in one of the mismatch repair (MMR) genes (MLH1, MSH2, MSH6 or PMS2), which encode proteins involved in a post-replicative proofreading and editing mechanism. The clinical presentation of LS is highly heterogeneous, showing high variability in age at onset and penetrance of cancer, which may be partly attributable to the molecular profiles of carcinomas. This review discusses the frequency of alterations in the WNT/B-CATENIN, RAF/MEK/ERK and PI3K/PTEN/AKT pathways identified in all four LS subgroups and how these changes may relate to the 'three pathway model' of carcinogenesis, in which LS CRCs develop from MMR-proficient adenomas, MMR-deficient adenomas or directly from MMR-deficient crypts. Understanding the specific differences in carcinogenesis for each LS subgroup will aid in the further optimization of guidelines for diagnosis, surveillance and treatment.

Challenges and perspectives for immunotherapy inoesophageal cancer: A look to the future (Review).

Oesophageal cancer is one of the most aggressive malignancies with limited treatment options, thus resulting in a high morbidity and mortality. With 5-year survival rates of only 5-10%, oesophageal cancer holds a dismal prognosis for patients. In order to improve overall survival, the early diagnosis and tools for patient stratification for personalized treatment are urgent needs. A minority of oesophageal cancers belong to the spectrum of Lynch syndrome-associated cancers and are characterized by microsatellite instability (MSI). Microsatellite instability is a consequence of defective mismatch repair protein functions and it has been well characterized in other gastrointestinal tumours, such as colorectal and gastric cancer. In the latter, high levels of MSI are associated with a better prognosis and with an increased benefit to immune-based therapies. Therefore, similar therapeutic approaches could offer an opportunity of treatment for oesophageal cancer patients with MSI. Apart from immune checkpoint inhibitors, other immunotherapies such as adoptive T-cell transfer, peptide vaccine and oncolytic viruses are under investigation in oesophageal cancer patients. In the present review, the rationale and current knowledge about immunotherapies in oesophageal cancer are summarised.

Immune-Based Therapies and the Role of Microsatellite Instability in Pancreatic Cancer.

Pancreatic cancer is one of the most aggressive malignancies with limited treatment options thus resulting in high morbidity and mortality. Among all cancers, with a five-year survival rates of only 2–9%, pancreatic cancer holds the worst prognostic outcome for patients. To improve the overall survival, an earlier diagnosis and stratification of cancer patients for personalized treatment options are urgent needs. A minority of pancreatic cancers belong to the spectrum of Lynch syndrome-associated cancers and are characterized by microsatellite instability (MSI). MSI is a consequence of defective mismatch repair protein functions and it has been well characterized in other gastrointestinal tumors such as colorectal and gastric cancer. In the latter, high levels of MSI are linked to a better prognosis and to an increased benefit to immune-based therapies. Therefore, the same therapies could offer an opportunity of treatment for pancreatic cancer patients with MSI. In this review, we summarize the current knowledge about immune-based therapies and MSI in pancreatic cancer.

Combined prognostic value of CD274 (PD-L1)/PDCDI (PD-1) expression and immune cell infiltration in colorectal cancer as per mismatch repair status

The CD274 (programmed cell death ligand-1, PD-L1)/PDCD1 (programmed cell death-1, PD-1) pathway is crucial suppressor of the cytotoxic immune response. Antibodies targeting CD274 or PDCD1 have been revealed to be effective in several malignancies. In colorectal cancer, the response to CD274/PDCD1 blockage is associated with microsatellite instability. However, the value of CD274/PDCD1 for predicting response to treatment or survival benefit is still unclear. The aims of the study were (1) to clarify differences in immune microenvironment and expression of checkpoint proteins (CD274/PDCD1) in DNA mismatch repair-proficient, mismatch repair-deficient, and hereditary Lynch syndrome-associated colorectal cancer, and (2) to assess the prognostic value of these factors and their combinations. Ninety-four mismatch repair-deficient colorectal cancers, 100 age, sex, and AJCC/UICC stage-matched mismatch repair-proficient colorectal cancers, and 48 Lynch syndrome-associated colorectal cancers were analyzed. Using whole section samples, detailed analysis of immune cell score, PDCD1, and CD274 expression was performed. Overlapping of CD274 expression in tumor and immune cells was almost complete (95%). Immune cell score and CD274/PDCD1 positivity were significantly more frequent in mismatch repair-deficient than in mismatch repair-proficient colorectal cancers (70% vs. 41% (high immune cell score); 81% vs. 49% (PDCD1high), 23% vs. 1% (CD274 on tumor cells) and 68% vs. 30% (CD274 on immune cells), P < 0.001), and were associated strongly with each other. Although the independent impact of immune cell score, PDCD1, and CD274 on immune cells was moderate, the immunoprofile parameter combining the above three factors appeared to be a strong independent prognostic factor for disease-specific survival and overall survival (P = 0.001) and had suggestive impact on disease-free survival (P = 0.011). Our results encourage the use of immune cell score analysis together with PDCD1 and CD274 detection to improve the prognostic evaluation of colorectal cancer patients. Particularly, the analyses from whole tissue sections are encouraged to allow reliable and cell-specific analyses of CD274 expression.

Targeted next-generation sequencing in the detection of mismatch repair deficiency in endometrial cancers

Mismatch repair deficiency represents a biomarker of immunotherapy response and a phenotypic feature of Lynch syndrome-associated endometrial cancers. Using a targeted next-generation sequencing assay, we identified molecular features of mismatch repair deficiency, specifically insertion and deletion mutations in mononucleotide repeats, and established thresholds for the number of such mutations to classify endometrial cancers as mismatch repair deficient, proficient, or indeterminate. Sequencing classification was compared to the loss of MLH1, MSH2, MSH6, or PMS2 expression by immunohistochemistry. A total of 259 endometrial cancers were classified by sequencing as mismatch repair deficient (n = 48, 19%), proficient (n = 199, 77%), or indeterminate (n = 12, 5%). Sequencing findings were concordant with loss of expression of at least one mismatch repair protein in 47 of 48 (98%) cases classified as deficient and retained expression of all four proteins in 190 of 199 (95%) cases classified as proficient. Of the 12 cases classified as indeterminate, 7 (58%) demonstrated mismatch repair protein loss. Overall, targeted next-generation sequencing exhibited a high rate of concordance with immunohistochemistry for mismatch repair deficiency; however, sequencing was indeterminate in a few cases and demonstrated a false negative rate of 5%. Although we recommend implementation of a mismatch repair deficiency algorithm for laboratories performing next-generation sequencing cancer panels, immunohistochemistry remains a cost-effective screening method for mismatch repair deficiency in endometrial cancer.

Defective DNA repair in hereditary ovarian cancers: Implications for therapy.

The role of mutated DNA repair pathways in hereditary ovarian cancer (OC) and the clinical basis for the use of poly(ADP-ribose) polymerase (PARP) enzyme inhibitors and an immune checkpoint inhibitor as novel targeted therapies in the treatment of certain OC subtypes are reviewed. OC is the most lethal of all gynecologic malignancies and encompasses a highly diverse collection of cancers. Hereditary OCs are a unique subtype of OC encompassing up to 24% of all OCs, including cancers driven by germline mutations of the BRCA1 or BRCA2 genes, mutations associated with Fanconi anemia (FA), BRCAness germline mutations, and Lynch syndrome. With an increasing wealth of genomic data available in cancer research, a common thread of defective DNA repair pathways as a primary driver of hereditary OCs has emerged. OCs driven by BRCA1/2, FA-associated, and BRCAness germline mutations have a demonstrated sensitivity to PARP inhibitors due to underlying deficiencies in DNA homologous recombination; however, clinical responses are often partial and highly dependent on platinum sensitivity. Additionally, the immune checkpoint inhibitor pembrolizumab is indicated for certain metastatic solid tumors characterized by microsatellite instability, a distinguishing feature highly associated with DNA mismatch repair deficiency in Lynch syndrome-associated cancers, including some OCs. In hereditary OC syndromes, mutations in DNA repair pathways form the clinical basis for the use of PARP inhibitors and an immune checkpoint inhibitor as novel targeted therapies.

Worldwide Practice Patterns in Lynch Syndrome Diagnosis and Management, Based on Data From the International Mismatch Repair Consortium

Families with a history of Lynch syndrome often do not adhere to guidelines for genetic testing and screening. We investigated practice patterns related to Lynch syndrome worldwide, to ascertain potential targets for research and public policy efforts. We collected data from the International Mismatch Repair Consortium (IMRC), which comprises major research and clinical groups engaged in the care of families with Lynch syndrome worldwide. IMRC institutions were invited to complete a questionnaire to characterize diagnoses of Lynch syndrome and management practice patterns. Fifty-five providers, representing 63 of 128 member institutions (49%) in 21 countries, completed the questionnaire. For case finding, 55% of respondents reported participating in routine widespread population tumor testing among persons with newly diagnosed Lynch syndrome-associated cancers, whereas 27% reported relying on clinical criteria with selective tumor and/or germline analyses. Most respondents (64%) reported using multigene panels for germline analysis, and only 28% reported testing tumors for biallelic mutations for cases in which suspected pathogenic mutations were not confirmed by germline analysis. Respondents reported relying on passive dissemination of information to at-risk family members, and there was variation in follow through of genetic testing recommendations. Reported risk management practices varied-nearly all programs (98%) recommended colonoscopy every 1 to 2 years, but only 35% recommended chemoprevention with aspirin. There is widespread heterogeneity in management practices for Lynch syndrome worldwide among IMRC member institutions. This may reflect the rapid pace of emerging technology, regional differences in resources, and the lack of definitive data for many clinical questions. Future efforts should focus on the large numbers of high-risk patients without access to state-of-the-art Lynch syndrome management.

Lynch Syndrome: Genomics Update and Imaging Review.

Lynch syndrome is the most common hereditary cancer syndrome, the most common cause of heritable colorectal cancer, and the only known heritable cause of endometrial cancer. Other cancers associated with Lynch syndrome include cancers of the ovary, stomach, urothelial tract, and small bowel, and less frequently, cancers of the brain, biliary tract, pancreas, and prostate. The oncogenic tendency of Lynch syndrome stems from a set of genomic alterations of mismatch repair proteins. Defunct mismatch repair proteins cause unusually high instability of regions of the genome called microsatellites. Over time, the accumulation of mutations in microsatellites and elsewhere in the genome can affect the production of important cellular proteins, spurring tumorigenesis. Universal testing of colorectal tumors for microsatellite instability (MSI) is now recommended to (a) prevent cases of Lynch syndrome being missed owing to the use of clinical criteria alone, (b) reduce morbidity and mortality among the relatives of affected individuals, and (c) guide management decisions. Organ-specific cancer risks and associated screening paradigms vary according to the sex of the affected individual and the type of germline DNA alteration causing the MSI. Furthermore, Lynch syndrome-associated cancers have different pathologic, radiologic, and clinical features compared with their sporadic counterparts. Most notably, Lynch syndrome-associated tumors tend to be more indolent than non-Lynch syndrome-associated neoplasms and thus may respond differently to traditional chemotherapy regimens. The high MSI in cases of colorectal cancer reflects a difference in the biologic features of the tumor, possibly with a unique susceptibility to immunotherapy. ©RSNA, 2018.

Clinicopathological characteristics of patients with upper urinary tract urothelial cancer with loss of immunohistochemical expression of the DNA mismatch repair proteins in universal screening.

To assess the detection rate of putative Lynch syndrome-associated upper urinary tract urothelial cancer among all upper urinary tract urothelial cancers and to examine its clinicopathological characteristics. A total of 143 patients with upper urinary tract urothelial cancer who had received total nephroureterectomy were immunohistochemically stained for the expression of mismatch repair proteins MLH1, PMS2, MSH2 and MSH6. For all suspected mismatch repair-deficient cases, MMR genetic testing was recommended and clinicopathological features were examined. Loss of mismatch repair proteins was found in seven patients (5%) who were thus categorized as putative Lynch syndrome-associated upper urinary tract urothelial cancer. Five of these patients showed dual loss of MSH2/MSH6. Two patients were confirmed to be MSH2 germline mutation carriers. Histologically, all seven tumors were low-grade atypical urothelial carcinoma and showed its unique histological features, such as an inverted papilloma-like growth pattern and a villous to papillary structure with mild stratification of tumor cells. Six tumors had no invasion of the muscularis propria. No recurrence or cancer-related deaths were reported in these seven patients. Just three patients met the revised Amsterdam criteria. This is the first report that universally examined mismatch repair immunohistochemical screening for upper urinary tract urothelial cancers. The prevalence (5%) of putative Lynch syndrome-associated upper urinary tract urothelial cancers is much higher than we had expected. We ascertained that putative Lynch syndrome-associated upper urinary tract urothelial cancers were clinically in the early stage and histologically classified into low-grade malignancy with its characteristic pathological features. The clinicopathological characteristics that we found in the present study could become additional possible markers in the diagnosis of Lynch syndrome-associated upper urinary tract urothelial cancers.

Germline multi-gene hereditary cancer panel testing in an unselected endometrial cancer cohort

AbstractHereditary endometrial carcinoma is associated with germline mutations in Lynch syndrome genes. The role of other cancer predisposition genes is unclear. We aimed to determine the prevalence of cancer predisposition gene mutations in an unselected endometrial carcinoma patient cohort. Mutations in 25 genes were identified using a next-generation sequencing-based panel applied in 381 endometrial carcinoma patients who had undergone tumor testing to screen for Lynch syndrome. Thirty-five patients (9.2%) had a deleterious mutation: 22 (5.8%) in Lynch syndrome genes (three MLH1, five MSH2, two EPCAM-MSH2, six MSH6, and six PMS2) and 13 (3.4%) in 10 non-Lynch syndrome genes (four CHEK2, one each in APC, ATM, BARD1, BRCA1, BRCA2, BRIP1, NBN, PTEN, and RAD51C). Of 21 patients with deleterious mutations in Lynch syndrome genes with tumor testing, 2 (9.5%) had tumor testing results suggestive of sporadic cancer. Of 12 patients with deleterious mutations in MSH6 and PMS2, 10 were diagnosed at age >50 and 8 did not have a family history of Lynch syndrome-associated cancers. Patients with deleterious mutations in non-Lynch syndrome genes were more likely to have serous tumor histology (23.1 vs 6.4%, P=0.02). The three patients with non-Lynch syndrome deleterious mutations and serous histology had mutations in BRCA2, BRIP1, and RAD51C. Current clinical criteria fail to identify a portion of actionable mutations in Lynch syndrome and other hereditary cancer syndromes. Performance characteristics of tumor testing are sufficiently robust to implement universal tumor testing to identify patients with Lynch syndrome. Germline multi-gene panel testing is feasible and informative, leading to the identification of additional actionable mutations.