Ras Point Mutations Research Articles

Abstract 1762: Characterization of somatic copy number deletion of chromosome 22q in papillary thyroid carcinoma

Abstract Deletion in the long arm of chromosome 22 (22qDEL) is the most prevalent somatic copy number alteration (SCNA) observed in papillary thyroid carcinoma (PTC). Despite its recurrence, the specific characteristics and role of 22qDEL in PTC have not been fully studied. We conducted a pooled analysis of 22qDEL by integrating patient and clinical information and molecular profiles from 1,094 primary PTC tumors across four major published PTC genomic studies: The Cancer Genome Atlas (TCGA) PTC profile study, the National Cancer Institute (NCI) post-Chornobyl PTC study, the Memorial Sloan Kettering Cancer Center Integrated Mutation Profiling of Actionable Cancer Targets (MSKCC-IMPACT) PTC cases, and the Seoul National University (SNU) thyroid cancer profile study. The majority of PTC with 22qDEL demonstrated arm-level loss of heterozygosity (86%). Even in PTC cases with partial 22qDEL, we observed a loss across 70% of chromosome 22, encompassing regions 22q12 and 22q13, which harbors known cancer genes (NF2 and CHEK2). More than 90% of 22qDEL co-occurred with established oncogenic drivers of PTC, though a full assessment of PTC drivers was not available for all cases. 22qDEL occurred more frequently with RAS point mutations (50.4%) than other drivers (9.3%). A higher fraction of 22qDEL was clonal in RAS-driven PTCs (78.3%), suggesting 22qDEL occurs early in RAS-driven tumor development. We did not observe any association between 22qDEL and established PTC risk factors such as age, sex, and radiation, nor with clinical features including tumor size, multifocality, and metastasis (p-values>0.22). RNA sequencing gene expression analysis based on 22qDEL status revealed downregulation of most genes residing on chromosome 22q and significant differential expression activity of immune-related genes, further implicating a role of immune dysregulation in PTC. Our study suggests that 22qDEL may not act as a primary driver of PTC but plays an important role as a co-factor of RAS point mutations, which could further drive PTC development. Citation Format: Olivia W. Lee, Danielle Karyadi, Stephen Hartley, Weyin Zhou, Mitchell Machiela, Mykola Tronko, Tetiana Bogdanova, Liudmyla Zurnadzhy, Lindsay Morton, Stephen Chanock. Characterization of somatic copy number deletion of chromosome 22q in papillary thyroid carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1762.

Molecular features of thyroid cancer in children

Background. Malignant neoplasms of the thyroid gland are the most common endocrine malignant neoplasms in the children’s age group. Unlike adults, who most often have BRAF and RAS mutations, children have chromosomal displacements. The relevance is explained by the lack of comprehensive studies on thyroid cancer in children in the Russian-language literature.The aim of the study is — to summarize and systematize the literature data on the molecular features of thyroid cancer in children.Materials and methods. The authors conducted a search for publications in the PubMed electronic database using the following algorithm: Molecular AND Thyroid cancer AND pediatrics. We found 451 publications, and after reviewing the annotations, 111 studies describing the molecular features of thyroid cancer in the pediatric population were included in the review. Publications were excluded due to duplication and inconsistency with the subject of this study.Results. Instead of point mutations of BRAF and RAS, characteristic of adults, regardless of radiation status, chromosomal displacements are more common in children. Re-arrangement of RET/PTC genes is the most common, followed by BRAF fusions. Mutations of the TERT promoter, which are markers of the aggressive course of the disease in adults, are rare in children. DICER1 mutations appear to play a key role in pediatric cases of follicular and papillary thyroid cancer. Medullary thyroid cancer (MTC) in children requires the exclusion of multiple endocrine neoplasia syndrome (MEN type 2). Tumors originating from follicular cells other than MTC can rarely be familial. Literature data on the role of microRNA as a biomarker in thyroid carcinomas in children is currently limited.

CRISPR/Cas9 Edited RAS & MEK Mutant Cells Acquire BRAF and MEK Inhibitor Resistance with MEK1 Q56P Restoring Sensitivity to MEK/BRAF Inhibitor Combo and KRAS G13D Gaining Sensitivity to Immunotherapy

BRAF V600E mutation drives uncontrolled cell growth in most melanomas. While BRAF V600E tumors are initially responsive to BRAF inhibitors, prolonged treatment results in inhibitor resistance and tumor regrowth. Clinical data have linked the NRAS Q61K, KRAS G13D and MEK1 Q56P mutations to the BRAF inhibitor resistance. However, development of novel therapeutics is hindered by the lack of relevant isogeneic cell models. We employed CRISPR/Cas9 genome engineering to introduce NRAS Q61K, KRAS G13D and MEK1 Q56P mutations into the A375 melanoma cell line with endogenously high expression of BRAF V600E. The resulting isogenic cell lines are resistant to BRAF inhibitors. The A375 MEK1 Q56P isogenic cells are additionally resistant to MEK inhibitors as single agent, but interestingly, these cells become sensitive to MEK/BRAF inhibitor combo. Our results suggest that resistance in the NRAS and MEK isogenic lines is driven by constitutive MEK/ERK signaling, while the resistance in the KRAS isogenic line is driven by EGFR overexpression. Interestingly, the KRAS G13D isogenic line displays elevated PD-L1 expression suggesting the KRAS G13D mutation could be a potential indication for immunotherapy. Overall, these three novel isogenic cell models with endogenous level RAS and MEK1 point mutations provide direct bio-functional evidence demonstrating that acquiring a drug-resistant gene drives tumor cell survival and may simultaneously introduce new indications for combo therapy or immunotherapy in the clinic.

RF11 | PSAT273 RET Gene Fusion In a Putative Case of Medullary Thyroid Cancer

Abstract Background Oncogenic RET gene fusions have been identified in non-small cell lung cancer and non-medullary thyroid cancers, whereas RET point mutations are the key genetic finding in both inherited and sporadic medullary thyroid cancer (MTC). The presence of a RET gene fusion provides a target for selective RET inhibitor drugs. We describe an unusual patient with suspected MTC and a positive RET gene fusion, with excellent response to targeted therapy. Clinical Case A 50-year-old male presented to our institution with cough, fatigue, heat intolerance, and flushing. His only remarkable history was stage IIIBS Hodgkin lymphoma treated with chemotherapy, in remission for approximately 6 years. CT chest revealed new bulky mediastinal and hilar adenopathy with bulky cervical nodes. VATS biopsy of a mediastinal node showed metastatic neuroendocrine neoplasm with plasmacytoid features that was immunoreactive for calcitonin, CEA and cytokeratin, but negative for TTF1 and PAX-8. The differential diagnosis included MTC or metastatic atypical carcinoid tumor. Next Generation Sequencing was negative, including RET and RAS point mutations. Subsequent testing for re-arrangements showed a KIF5B-RET gene fusion, an oncogene identified in lung adenocarcinoma. Biochemical findings showed a calcitonin level of 16,033 (normal < 10 pg/mL) and CEA 6.9 (normal < 4.7 ng/mL). Chromogranin A was 146.6 (normal < 101.16 ng/mL). ACTH and cortisol were normal. Neck US revealed a calcified 5 mm right upper pole thyroid nodule and extensive bilateral cervical nodes. A provisional diagnosis was made of MTC. Vandetanib was started. Two months later, he reported worsening orthopnea, diarrhea, and weight loss. CT chest showed marked worsening with enlarging mediastinal hilar and supraclavicular adenopathy with new moderate sized pericardial and pleural effusion. Vandetanib was discontinued and Selpercatinib started, following FDA approval. He reported prompt resolution of dyspnea and diarrhea and improved weight and energy. Calcitonin declined to <2 pg/mL, and CEA to1.6 ng/mL four months into treatment. CT neck showed marked shrinkage of lymph nodes with a persistent calcified thyroid nodule. CT chest showed marked shrinkage of mediastinal and hilar masses, with resolution of bronchial narrowing and right pleural effusion. Nine months after presentation, there were no chest symptoms and biochemical markers and imaging remained stable. Conclusion Approximately 25% of MTC tumors lack activating point mutations in RET or RAS genes. Analysis of actionable fusion mutations should be considered if there is metastatic disease. High serum calcitonin levels are not pathognomonic for MTC and tumor histology may overlap with neuroendocrine lung cancers, creating a diagnostic challenge. Depending on whether this patient's tumor originated in the thyroid gland, it may represent an unusual case of RET gene fusion in MTC. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m., Saturday, June 11, 2022 1:00 p.m. - 1:05 p.m.

Epidemiology of Thyroid Cancer.

Epidemiology of Thyroid Cancer.

Stabilization of the RAS:PDE6D Complex Is a Novel Strategy to Inhibit RAS Signaling.

RAS is a major anticancer drug target which requires membrane localization to activate downstream signal transduction. The direct inhibition of RAS has proven to be challenging. Here, we present a novel strategy for targeting RAS by stabilizing its interaction with the prenyl-binding protein PDE6D and disrupting its localization. Using rationally designed RAS point mutations, we were able to stabilize the RAS:PDE6D complex by increasing the affinity of RAS for PDE6D, which resulted in the redirection of RAS to the cytoplasm and the primary cilium and inhibition of oncogenic RAS/ERK signaling. We developed an SPR fragment screening and identified fragments that bind at the KRAS:PDE6D interface, as shown through cocrystal structures. Finally, we show that the stoichiometric ratios of KRAS:PDE6D vary in different cell lines, suggesting that the impact of this strategy might be cell-type-dependent. This study forms the foundation from which a potential anticancer small-molecule RAS:PDE6D complex stabilizer could be developed.

Updates in the advances of sporadic medullary thyroid carcinoma: from the molecules to the clinic.

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine malignancy that originates in parafollicular cells. It is well-known that a quarter of MTC are involved in hereditary multiple endocrine neoplasia type 2 syndromes, whereas most MTC are sporadic. Unlike the commonly encountered gastrointestinal or pulmonary neuroendocrine tumors, most sporadic MTCs have distinct genetic alterations featured by somatic changes of either Rearranged during Transfection (RET) or RAS point mutation. The increasing application of next-generation sequencing, whole-exome sequencing, and other molecular detection techniques enables us to understand MTC comprehensively concerning its detailed molecular changes and their clinical correlations. This article reviews the advances in genetic alterations and their prognostic impact in sporadic MTC among different populations and discusses the associated tumor immune microenvironments and the potential role of immunotherapy targeting PD-L1/PD-1 in treating MTC. Furthermore, the current multikinase inhibitor targeting therapy for sporadic MTC has been summarized here and its efficacy and drug toxicity are discussed. Updates in advance of the role of calcitonin/procalcitonin/calcitonin-related polypeptide alpha (CALCA) gene transcripts in diagnosing and handling MTC are also mentioned. The treatment of advanced MTC is still challenging and might require a combination of several modalities.

Emerging RAS, BRAF, and EGFR mutations in cell-free DNA of metastatic colorectal patients are associated with both primary and secondary resistance to first-line anti-EGFR therapy.

Oncogenic RAS mutations are negative biomarkers of response to epidermal growth factor receptor (EGFR) blockade. RAS mutations are usually detected in biopsies of primary colorectal tumors. However, the genomic profiles of primary tumors and metastases are not always concordant, and chemotherapeutic agents can alter the tumor molecular landscape. Cell-free DNA (cfDNA) is a novel tool to detect molecular heterogeneity. This study evaluated the clinical utility of cfDNA to predict primary or secondary resistance to EGFR blockade in patients with metastatic colorectal cancer. Thirty metastatic colorectal cancer patients without RAS and BRAF mutations were prospectively enrolled and treated with cytotoxic agents and EGFR blockade as first-line therapy. cfDNA was analyzed for the presence of RAS, BRAF, and EGFR (S492R) point mutations before initiating chemotherapy and every 2months during chemotherapy. The analysis was performed in 223 plasma samples from all 30 patients. Of the 30 patients, five had RAS mutations in their cfDNA before starting chemotherapy and did not respond. Twenty-four of the remaining 25 patients without cfDNA RAS mutations had a response. Twenty of the 24 responders developed secondary resistance and cfDNA RAS mutations were found in 17 of the 20. cfDNA BRAF mutations were found in seven, and EGFR mutations were found in eight of the 20 patients. Emerging RAS, BRAF, and EGFR mutations occurred in patients with primary and secondary resistance to EGFR blockade. The detection of these mutations in cfDNA is a promising approach to predict treatment response and secondary resistance.

With AMG 510, the Treatment of Non Small Cell Lung Cancer Has Been Changed

There are 3 types of RAS oncogene, K RAS, N RAS, H RAS. This RAS can be diagnosed through Real Time PCR. H RAS point mutation is responsible for bladder cancer whereas N RAS point mutation is responsible for Hematopoietic tumors. K RAS point mutation is most important and it cause NON SMALL CELL LUNG CANCER, Carcinoma of Colon, Carcinoma of pancreas. K RAS is the molecular on/off switch. When turned on, it recruits and activates proteins necessary for the proliferation of growth factor and their receptors’ signal such as c-Raf and PI 3-kinase. In Combination with GTP, KRAS possesses an intrinsic enzymatic activity which cleaves the terminal phosphate of the nucleotide, and finally make itself turn off. For over 30 years, the protein KRAS is a major challenge in drug design. So far, there is no approved therapy for patients with KRAS mutations, which comprise around 25% of patients with lung cancer. Achilles heel small molecules in K RAS G12C, subverting the native nucleotide preference to favour GDP over GTP and impairing binding to Raf. Dr. Nathanael S. Gray, in the Department of Cancer Biology at the Dana-Farber Cancer Institute, reported the synthesis of a GDP analogue(SML-8-73-1) and a prodrug derivative (SML-10-70-1), which were selective, direct-acting covalent inhibitors of the KRAS (G12C) mutant relative to wild-type Ras. An orally available agent that targets the specific KRAS mutation, p.G12C, with potential anti-neoplastic activity. Upon oral administration, KRAS mutant-targeting AMG 510 selectively targets the KRAS p.G12C mutant, at either the DNA, RNA or protein level, and prevents, through an as of yet not elucidated manner, expression of and/or tumor cell signaling through the KRAS p.G12C mutant. This may inhibit growth in KRAS p.G12C-expressing tumor cells. The KRAS p.G12C mutation is seen in some tumor cell types and plays a key role in tumor cell proliferation.

RAS-MPAK Pathway Signaling in Health and Disease

The p21ras (Ras) family of signal switch molecules is an essential component of proliferative responses to many extracellular stimuli including most hematopoietic growth factors and cytokines. Phosphorylation of tyrosine residues on activated cytokine/growth factor receptors triggers multiple signaling pathways including JAK/STAT, Ras and PI3K. Activated Ras proteins further activate downstream effectors such as RAF/MEK/ERK, PI3K and RalGDS. Point mutations of Ras proteins are commonly found in human cancers and are estimated to occur in about 30% of cancer cases. These mutations lock Ras in the constitutively active conformation. In addition to point mutations of RAS, other genetic lesions such as the BCR-ABL fusion, PTPN11 mutations, FLT3 internal tandem duplications, CBL mutations and NF1 inactivation all lead to hyperactive Ras signaling. Besides cancers, RAS and Ras-activating mutations have been found in RASopathies, such as Neurofibromatosis type 1 (NF1), Noonan Syndrome, Costello syndrome, and Cardiofaciocutaneous syndrome (CFC).RAS mutations are highly prevalent in hematologic malignancies including chronic and juvenile myelomonocytic leukemia (CMML and JMML), acute myeloid leukemia (AML), acute lymphocytic leukemia (ALL) and multiple myeloma (MM). In contrast to epithelial cancers where KRAS mutations are highly prevalent, most mutations found in hematologic malignancies alter NRAS. Human genetic data and results from genetic mouse models support the idea that deregulated Ras signaling is initiating event in myeloproliferative neoplasms (MPNs) and MPN/MDS overlapping diseases. RAS mutations are detected among the initiating mutations in many cases of CMML and JMML, and can persist in patients who have achieved remission either spontaneously or after treatment. Furthermore, mutations of Nras and Kras, as well as leukemia-associated mutations that result in hyperactive Ras such as BCR-ABL, loss of NF1, PTPN11 or CBL mutations all induce MPN or MPN/MDS overlapping disease in mouse models. Although in adult de novo AMLs, human genetic data support a model in which RAS and Ras-activation mutations are likely secondary event, recent large scale next generation sequencing studies show that RAS and Ras-activating mutations are much more commonly found in pediatric than adult AML cases, and pediatric AMLs in general lack “adult pre-leukemic mutation' such as TET2, DNMAT3 or IDH1/2. These results suggest a possibility that RAS mutations can be initiating mutations in pediatric AMLs. In addition, even in AMLs where RAS mutations are secondary event, hyperactive Ras promotes leukemic stem cell self-renewal and is critical for leukemia maintenance, underscoring the importance of targeting Ras for leukemia treatment.Targeting Ras proteins remains to be challenging and significant ongoing effort focuses on developing direct inhibitors of Ras. In recent years, small molecules that bind to Ras proteins to prevent GEF-mediated GDP/GTP exchange, or target the RasG12C mutant allele, showed promising pre-clinical results. Besides, targeting Ras effectors, such as MEK/ERK, individually or in combination with other pathways, remains as a valid approach to halt Ras-induced malignant proliferation. Better understanding of the subcellular localization, feedback regulation and redundancy of Ras-activated signaling network under physiological and pathological contexts will shed light on developing new strategies to effectively attack Ras-driven cancers. DisclosuresNo relevant conflicts of interest to declare.

Molecular pathology of thyroid tumours of follicular cells: a review of genetic alterations and their clinicopathological relevance.

Thyroid cancer is the most common endocrine malignancy. Knowledge of the molecular pathology of thyroid tumours originating from follicular cells has greatly advanced in the past several years. Common molecular alterations, such as BRAF p.V600E, RAS point mutations, and fusion oncogenes (RET-PTC being the prototypical example), have been, respectively, associated with conventional papillary carcinoma, follicular-patterned tumours (follicular adenoma, follicular carcinoma, and the follicular variant of papillary carcinoma/non-invasive follicular thyroid neoplasm with papillary-like nuclear features), and with papillary carcinomas from young patients and arising after exposure to ionising radiation, respectively. The remarkable correlation between genotype and phenotype shows how specific, mutually exclusive molecular changes can promote tumour development and initiate a multistep tumorigenic process that is characterised by aberrant activation of mitogen-activated protein kinase and phosphoinositide 3-kinase-PTEN-AKT signalling. Molecular alterations are becoming useful biomarkers for diagnosis and risk stratification, and as potential treatment targets for aggressive forms of thyroid carcinoma. What follows is a review of the principal genetic alterations of thyroid tumours originating from follicular cells and of their clinicopathological relevance.

Resistance of papillary thyroid cancer stem cells to chemotherapy.

Thyroid carcinoma is the most common endocrine neoplasm, with the highest mortality rate of all the endocrine cancers. Among the endocrine malignancies, ~80% are papillary thyroid carcinomas (PTCs). In the initiation and progression of this tumor, genetic alterations in the mitogen-associated protein kinase pathway, including RAS point mutations, RET/PTC oncogene rearrangements and BRAF point mutations, play an important role, particularly in deciding targeted therapy. In the present study, a small population of thyroid tumor cells, known as tumor spheres, were isolated and characterized from PTC surgical samples. These spheres can be expanded indefinitely in vitro and give rise to differentiated adherent cells when cultivated in differentiative conditions. The present study showed by reverse transcription-polymerase chain reaction and flow cytometric analysis that the undifferentiated PTC cells exhibited a characteristic antigen expression profile of adult progenitor/stem cells. The cells were more resistant to chemotherapeutics, including bortezomib, taxol, cisplatin, etoposide, doxorubicin and vincristine, than differentiated PTC cells and the majority possessed a quiescent status, as revealed by the various cell cycle characteristics and anti-apoptotic protein expression. Such advances in cancer thyroid stem cell biology may provide relevant information for future targeted therapies.

Mutation in BRAF and Other Members of the MAPK Pathway in Papillary Thyroid Carcinoma in the Pediatric Population.

Papillary thyroid carcinoma (PTC) is an uncommon tumor in the pediatric population. A limited number of studies have examined genetic mutations affecting the mitogen-activated protein kinase (MAPK) pathway in the pediatric population. To examine mutations affecting this pathway in PTC in our pediatric population and compare the BRAF V600E mutation rates in pediatric and adult tumors. Eighty-four patients, including 14 pediatric and 70 adult, with PTC were tested for the BRAF V600E mutation by using real-time polymerase chain reaction and sequencing. Additionally, we examined the rate of RAS point mutations with real-time polymerase chain reaction and rearrangements of RET/PTC1 and RET/PTC3 in the pediatric group with fluorescence in situ hybridization. Clinical and histologic data were compared as well. Of 77 tumors that had an interpretable result, the BRAF V600E mutant was identified in 4 of 13 pediatric patients (31%) and 43 of 64 adult patients (67%), which was a significant difference (using Fisher exact test, P = .03). One pediatric and 6 adult cases did not reveal an interpretable result with melting curve analysis. One of these cases harbored a rare 3-base pair deletion mutation (c.1799_1801delTGA). Mutations in RAS genes were not seen in any pediatric tumors. One tumor with a RET/PTC1 rearrangement and another with RET/PTC3 were identified in the pediatric population (15%). The rate of the BRAF V600E mutation in the pediatric population is significantly lower than that seen in the adult population. Mutations in RAS do not contribute significantly to pediatric PTC. This experience from our institution adds to the growing body of knowledge regarding tumor genetics in pediatric PTC.

Molecular Diagnosis Using Residual Liquid-Based Cytology Materials for Patients with Nondiagnostic or Indeterminate Thyroid Nodules.

BackgroundMolecular analysis for common somatic mutations in thyroid cancer can improve diagnostic accuracy of fine-needle aspiration cytology (FNAC) in the nondiagnostic or indeterminate category of thyroid nodules. In this study, we evaluated the feasibility of molecular diagnosis from residual liquid-based cytology (LBC) material after cytological diagnosis.MethodsThis prospective study enrolled 53 patients with thyroid nodules diagnosed as nondiagnostic, atypia of undetermined significance (AUS), or follicular lesion of undetermined significance (FLUS) after FNAC. DNAs and RNAs were isolated from residual LBC materials. BRAFV600E and RAS point mutations, PAX8/peroxisome proliferator-activated receptor γ (PPARγ), RET/PTC1, and RET/PTC3 rearrangements were evaluated by real-time polymerase chain reaction and pyrosequencing.ResultsAll DNAs from 53 residual LBC samples could be analysed and point mutations were detected in 10 samples (19%). In 17 AUS nodules, seven samples (41%) had point mutations including BRAF (n=4), NRAS (n=2), and KRAS (n=1). In 20 FLUS nodules, three samples (15%) had NRAS point mutations. RNA from only one FLUS nodule could be analysed for rearrangements and there was no abnormality.ConclusionMolecular analysis for BRAF and RAS mutations was feasible in residual LBC materials and might be useful for diagnosis of indeterminate thyroid nodules.

Histopathological features of papillary thyroid carcinomas detected during four screening examinations of a Ukrainian-American cohort.

Background:There are limited data on the histopathology of papillary thyroid carcinomas (PTCs) diagnosed in irradiated populations. We evaluated the associations between iodine-131 dose and the histopathological characteristics of post-Chernobyl PTCs, the changes in these characteristics over time, and their associations with selected somatic mutations.Methods:This study included 115 PTCs diagnosed in a Ukrainian-American cohort (n=13 243) during prescreening and four successive thyroid screenings. Of these PTCs, 65 were subjected to somatic mutation profiling. All individuals were <18 years at the time of the Chernobyl accident and had direct thyroid radioactivity measurements. Statistical analyses included multivariate linear and logistic regression.Results:We identified a borderline significant linear-quadratic association (P=0.063) between iodine-131 dose and overall tumour invasiveness (presence of extrathyroidal extension, lymphatic/vascular invasion, and regional or distant metastases). Irrespective of dose, tumours with chromosomal rearrangements were more likely to have lymphatic/vascular invasion than tumours without chromosomal rearrangements (P=0.020) or tumours with BRAF or RAS point mutations (P=0.008). Controlling for age, there were significant time trends in decreasing tumour size (P<0.001), the extent of lymphatic/vascular invasion (P=0.005), and overall invasiveness (P=0.026).Conclusions:We determined that the invasive properties of PTCs that develop in iodine-131-exposed children may be associated with radiation dose. In addition, based on a subset of cases, tumours with chromosomal rearrangements appear to have a more invasive phenotype. The increase in small, less invasive PTCs over time is a consequence of repeated screening examinations.

Molecular analysis of residual ThinPrep material from thyroid FNAs increases diagnostic sensitivity.

Molecular testing for genetic alterations associated with malignancy is a potential triage approach for thyroid fine-needle aspiration (FNA) samples with indeterminate cytology. Because liquid-based FNA material allows for efficient RNA extraction, the authors analyzed residual material for common point mutations and rearrangements. Thyroid FNAs were classified according to The Bethesda System for Reporting Thyroid Cytopathology after routine ThinPrep slide preparation. Residual samples from malignant and indeterminate cases were submitted for molecular analysis, along with a random cohort of nondiagnostic and benign aspirates. Blinded analysis of BRAF and RAS point mutations and RET/PTC and PAX8/PPARγ rearrangements was correlated with subsequent follow-up. Adequate results were obtained in 402 of 597 cases (67%). Mutations or rearrangements were detected in 24 of 117 cytologically indeterminate specimens (21%) (17 RAS rearrangements, 6 BRAF rearrangements, and 1 PAX8/PPARγ rearrangement). BRAF mutations were preferentially associated with malignant cytologic diagnoses (22 of 42 cases; 52%), with less frequent detection in the suspicious for malignancy category (4 of 27 cases; 15%) and very low detection in all other categories (1%-4%). Surgical follow-up confirmed malignancy in all 21 BRAF-mutated cases, 42% of RAS-mutated cases (10 of 24 cases), and 37% of cases with no detected mutation (39 of 105 cases). Molecular analysis is feasible on residual ThinPrep material with the advantage of not requiring additional FNA procedures. The majority of BRAF mutations are identified in cases classified cytologically as malignant, and, to a lesser extent, as suspicious for malignancy. The usefulness of BRAF testing is limited by the low rate of BRAF-positive cases in other categories, thereby highlighting the need to identify other genetic drivers of clinically aggressive thyroid cancers.

Relevance of BRAF(V600E) mutation testing versus RAS point mutations and RET/PTC rearrangements evaluation in the diagnosis of thyroid cancer.

A molecular profile including BRAF and RAS mutations as well as RET/PTC rearrangement evaluation has been proposed to provide an accurate presurgical assessment of thyroid nodules and to reduce the number of unnecessary diagnostic surgeries, sparing patients' health and saving healthcare resources. However, the application of such molecular analyses may provide different results among different centers and populations in real-life settings. Our aims were to evaluate the diagnostic utility of assessing the presence of BRAF and RAS mutations and RET/PTC1 and RET/PTC3 rearrangements in all cytological categories in an Italian group of thyroid nodule patients assessed prospectively, and to understand whether and which mutation testing might be helpful in cytologically indeterminate nodules. A total of 911 patients were submitted to ultrasound and fine-needle aspiration biopsy examination. Cytological evaluation was performed in parallel with molecular testing and compared to pathological results in 940 thyroid nodules, including 140 indeterminate lesions. BRAF mutation testing provided the best contribution to cancer diagnosis, allowing the disease to be detected at an early stage, and identifying indeterminate nodules in which diagnostic lobectomy could be spared. On the contrary, RAS and RET/PTC analysis did not further increase diagnostic sensitivity for thyroid cancer. In addition, we found RET/PTC rearrangements in benign lesions, indicating that this molecular marker might not be useful for the detection of thyroid cancer. BRAF(V600E) mutation analysis is superior to RAS point mutations and evaluation of RET/PTC rearrangements in the diagnosis of thyroid cancer, even in indeterminate lesions.

Molecular diagnostics of fine needle aspiration for the presurgical screening of thyroid nodules.

“The incidence of thyroid cancer, the most common endocrine malignancy, is rising. The two most common types of thyroid cancer are papillary and follicular” thyroid carcinomas. “Fine-needle aspiration (FNA) of thyroid nodules” can permit to detect many genetic mutations and other molecular alterations, including RAS and BRAF point mutations, PAX8/peroxisome proliferator-activated receptor (PPAR)γ and “RET/PTC rearrangements, occurring in thyroid papillary and follicular carcinomas” (more than 70% of cases), which can be used successfully to improve the diagnosis “and the management of patients with thyroid nodules”. The most extensive experience has been accumulated with “the diagnostic use of BRAF mutation”, which is highly specific for malignancy. “Testing FNA samples for a panel of mutations” that typically includes RAS, BRAF, PAX8/PPARγ and RET/PTC could permit to achieve the biggest diagnostic impact. “The accuracy of cancer diagnosis in thyroid nodules could be improved significantly using these and other emerging molecular markers”.

Feinnadelzytologie von Schilddrüsenknoten: Molekulare Diagnostik in der klinischen Routine

Results for the detection of point mutations and rearrangements have thus far been obtained by fresh material of fine needle aspiration cytology (FNAC). After a first retrospective study we report on the diagnostic detection in routinely obtained, consecutive air-dried FNAC smears. RNA and DNA was extracted from 154 consecutive routine air-dried FNAC smears: 80 with microfollicular proliferation (MFP), 45 with follicular neoplasia (FN), 26 with the cytological diagnosis of papillary carcinomas (PTC) and 3 which were suspicious for malignancy. PAX8/PPARG and RET/PTC3 rearrangements were detected by qPCR, while BRAF and RAS point mutations were detected by pyrosequencing. Only 0.7 % and 5.3 % of the routine air-dried FNAC samples did not allow analysis of a point mutation or rearrangements, respectively. NRAS mutations could be detected in 7 MFP smears, and in one of FN and PTC samples, respectively. HRAS mutations were detected in one MPF and one FN sample. A KRAS mutation was only detected in one FN sample, whereas BRAF mutations were detected in 20 samples with PTC (but in no other sample). PAX8/PPARG was detected in 2 MFP samples, while RET/PTC was detected in only one MFP sample. In total, 13.8 % MFP-FNAC, 6.7 % FN-FNAC, and 80.8 % PTC-FNAC samples harbored a mutation. These results demonstrate that rearrangements and point mutations can be detected in routinely obtained air-dried FNAC samples.

The Increase in Thyroid Cancer Incidence During the Last Four Decades Is Accompanied by a High Frequency ofBRAFMutations and a Sharp Increase inRASMutations

Thyroid cancer incidence rates in the United States and globally have increased steadily over the last 40 years, primarily due to a tripling of the incidence of papillary thyroid carcinoma (PTC).The purpose of this study was to analyze trends in demographic, clinical, pathologic, and molecular characteristics of PTC from 1974 to 2009.We identified and histologically reviewed 469 consecutive cases of PTC from one US institution from 4 preselected periods (1974 to 1985, 1990 to 1992, 2000, and 2009) and assessed BRAF and RAS point mutations and RET/PTC rearrangements among 341 tumors ≥0.3 cm in size. Changes over time were analyzed using polytomous and binary logistic regression; all analyses were adjusted for age and sex.During this period, the median age of patients at diagnosis increased from 37 to 53 years (P < .001) and the percentage of microcarcinomas (≤1.0 cm) increased from 33% to 51% (P < .001), whereas extrathyroidal extension and advanced tumor stage decreased from 40% to 21% (P = .005) and from 43% to 28% (P = .036), respectively. Changes in tumor histopathology showed a decrease in classic PTC and an increase in the follicular variant (P < .001). The proportion of tumors with a BRAF mutation was stable (∼46%) but increased from 50% to 77% (P = .008) within classic papillary PTCs. The proportion of tumors with RAS mutations increased from 3% to 25% and within follicular pattern tumors from 18% to 44% (P < .001). The proportion of RET/PTC rearrangements decreased from 11% to 2% (P = .038).Similar to US national trends, we found an increasing age at diagnosis and greater detection of smaller-sized intrathyroidal PTCs. However, the overall proportion of BRAF mutations remained stable. Sharply rising percentages of the follicular variant histology and RAS mutations after 2000 suggest new and more recent etiologic factors. The increased incidence is not likely to be due to environmental or therapeutic radiation because the percentage of RET/PTC rearrangements decreased.