To describe the evolution and clinical utility of molecular testing for thyroid nodules and cancer achieved over the last 2 decades.
Scientific reports on thyroid cancer genetics and molecular ...diagnostics in thyroid nodules.
Over the last 2 decades, our understanding of the genetic mechanisms of thyroid cancer has dramatically expanded, such that most thyroid cancers now have known gene driver events. This knowledge provides the basis for establishing and further improving molecular tests for thyroid nodules and cancer and for the introduction of new entities such as noninvasive follicular thyroid neoplasm with papillary-like nuclear features. The progress with molecular tests for thyroid nodules started in the 1990s from demonstrating feasibility of detecting various molecular alterations in fine-needle aspiration (FNA) material collected from thyroid nodules. It was followed by the introduction of the first single-gene mutational markers, such as BRAF, and a small mutational panel into clinical practice in the mid 2000s. Currently, several more advanced molecular tests are available for clinical use. They are based on multiple molecular markers and have increasing impact on the clinical management of patients with thyroid nodules.
The evolution of molecular tests for thyroid nodules followed the discovery of various diagnostic and prognostic molecular markers of thyroid cancer that can be applied to thyroid FNA samples to inform more individualized management of these patients.
FNA = fine-needle aspiration miRNA = micro RNA NGS = next-generation sequencing NIFTP = noninvasive follicular thyroid neoplasm with papillary-like nuclear features NPV = negative predictive value PPV = positive predictive value PTC = papillary thyroid carcinoma RAI = radioactive iodine.
Thyroid cancer is the most common type of endocrine malignancy and its incidence is steadily increasing. Papillary carcinoma and follicular carcinoma are the most common types of thyroid cancer and ...represent those tumor types for which use of molecular markers for diagnosis and prognostication is of high clinical significance.
To review the most common molecular alterations in thyroid cancer and their diagnostic and prognostic utility.
PubMed (US National Library of Medicine)-available review articles, peer-reviewed original articles, and experience of the author.
The most common molecular alterations in thyroid cancer include BRAF and RAS point mutations and RET/PTC and PAX8/PPAR γ rearrangements. These nonoverlapping genetic alterations are found in more than 70% of papillary and follicular thyroid carcinomas. These molecular alterations can be detected in surgically resected samples and fine-needle aspiration samples from thyroid nodules and can be of significant diagnostic use. The diagnostic role of BRAF mutations has been studied most extensively, and recent studies also demonstrated a significant diagnostic utility of RAS, RET/PTC, and PAX8/PPAR γ mutations, particularly in thyroid fine-needle aspiration samples with indeterminate cytology. In addition to the diagnostic use, BRAF V600E mutation can also be used for tumor prognostication, as this mutation is associated with higher rate of tumor recurrence and tumor-related mortality. The use of these and other emerging molecular markers is expected to improve significantly the accuracy of cancer diagnosis in thyroid nodules and allow more individualized surgical and postsurgical management of patients with thyroid cancer.
Thyroid cancer is the most common malignant tumor of the endocrine system. The most frequent type of thyroid malignancy is papillary carcinoma. These tumors frequently have genetic alterations ...leading to the activation of the mitogen-activated protein kinase (MAPK) signaling pathway. Most common mutations in papillary carcinomas are point mutations of the BRAF and RAS genes and RET/PTC rearrangement. These genetic alterations are found in >70% of papillary carcinomas and they rarely overlap in the same tumor. Most frequent alterations in follicular carcinomas, the second most common type of thyroid malignancy, include RAS mutations and PAX8-PPARgamma rearrangement. RET point mutations are crucial for the development of medullary thyroid carcinomas. Many of these mutations, particularly those leading to the activation of the MAPK pathway, are being actively explored as therapeutic targets for thyroid cancer. A number of compounds have been studied and showed antitumor effects in preclinical studies and are being tested in ongoing clinical trials.
In the recent years, a large number of molecular alterations in thyroid cancer has been discovered and characterized. Some of these markers may have significant diagnostic utility, can be used for ...tumor prognostication, and serve as potential therapeutic targets. The diagnostic utility of these markers is of particular importance in thyroid fine-needle aspiration samples. Some molecular markers, such as BRAF, offer help in risk stratification and can be potentially used to optimize surgical and postsurgical management of patients with thyroid cancer. This review discusses major molecular alterations known to occur in thyroid cancer, focusing on those markers that have been extensively characterized, carry clinical significance, and are being introduced into pathology practice.
Objectives:
Next-generation sequencing (NGS) allows for high-throughput sequencing analysis of large regions of the human genome. We explored the use of targeted NGS for simultaneous testing for ...multiple mutations in thyroid cancer.
Design:
A custom panel (ThyroSeq) was designed to target 12 cancer genes with 284 mutational hot spots. Sequencing was performed to analyze DNA from 228 thyroid neoplastic and nonneoplastic samples including 105 frozen, 72 formalin-fixed, and 51 fine-needle aspiration samples representing all major types of thyroid cancer.
Results:
Only 5–10 ng of input DNA was sufficient for successful analysis of 99.6% of samples. The analytical accuracy for mutation detection was 100% with the sensitivity of 3%–5% of mutant allele. ThyroSeq DNA assay identified mutations in 19 of 27 of classic papillary thyroid carcinomas (PTCs) (70%), 25 of 30 follicular variant PTCs (83%), 14 of 18 conventional (78%) and 7 of 18 oncocytic follicular carcinomas (39%), 3 of 10 poorly differentiated carcinomas (30%), 20 of 27 anaplastic (ATCs) (74%), and 11 of 15 medullary thyroid carcinomas (73%). In contrast, 5 of 83 benign nodules (6%) were positive for mutations. Most tumors had a single mutation, whereas several ATCs and PTCs demonstrated two or three mutations. The most common mutations detected were BRAF and RAS followed by PIK3CA, TP53, TSHR, PTEN, GNAS, CTNNB1, and RET. The BRAF mutant allele frequency was 18%–48% in PTCs and was lower in ATCs.
Conclusions:
The ThyroSeq NGS panel allows simultaneous testing for multiple mutations with high accuracy and sensitivity, requires a small amount of DNA and can be performed in a variety of thyroid tissue and fine-needle aspiration samples, and provides quantitative assessment of mutant alleles. Using this approach, the point mutations were detected in 30%–83% of specific types of thyroid cancer and in only 6% of benign thyroid nodules and were shown to be present in the majority of cells within the cancer nodule.
Thyroid cancer is a common type of endocrine malignancy, and its incidence has been steadily increasing in many regions of the world. Initiation and progression of thyroid cancer involves multiple ...genetic and epigenetic alterations, of which mutations leading to the activation of the MAPK and PI3K-AKT signaling pathways are crucial. Common mutations found in thyroid cancer are point mutation of the BRAF and RAS genes as well as RET/PTC and PAX8/PPARγ chromosomal rearrangements. The mutational mechanisms seem to be linked to specific etiologic factors. Chromosomal rearrangements have a strong association with exposure to ionizing radiation and possibly with DNA fragility, whereas point mutations probably arise as a result of chemical mutagenesis. A potential role of dietary iodine excess in the generation of BRAF point mutations has also been proposed. Somatic mutations and other molecular alterations have been recognized as helpful diagnostic and prognostic markers for thyroid cancer and are beginning to be introduced into clinical practice, to offer a valuable tool for the management of patients with thyroid nodules.
The molecular foundations of Hürthle cell carcinoma (HCC) are poorly understood. Here we describe a comprehensive genomic characterization of 56 primary HCC tumors that span the spectrum of tumor ...behavior. We elucidate the mutational profile and driver mutations and show that these tumors exhibit a wide range of recurrent mutations. Notably, we report a high number of disruptive mutations to both protein-coding and tRNA-encoding regions of the mitochondrial genome. We reveal unique chromosomal landscapes that involve whole-chromosomal duplications of chromosomes 5 and 7 and widespread loss of heterozygosity arising from haploidization and copy-number-neutral uniparental disomy. We also identify fusion genes and disrupted signaling pathways that may drive disease pathogenesis.
•HCCs have a high number of mutations, several of which regulate translation•HCCs exhibit a high number of somatic recurrent mitochondrial mutations•HCCs have a unique chromosomal landscape, which predicts aggressive behavior•Several recurrent fusion genes, including TMEM233_PRKAB1, are identified
Ganly et al. elucidate recurrent mutations impacting the RTK/RAS/AKT/mTOR pathway, DNA damage/repair, epigenetic modifiers, TERT promoter, and the mitochondrial genome in Hürthle cell carcinoma (HCC). HCCs also display prevalent chromosome 5 and 7 duplications, loss of heterozygosity, and in-frame gene fusions.
Objective: MicroRNA (miRNA) expression is deregulated in many types of human cancers. We sought to investigate the expression patterns of miRNA in all major types of thyroid tumors, including tumors ...carrying distinct oncogenic mutations, and to explore the utility of miRNA profiling for the preoperative diagnosis of thyroid nodules.
Design: miRNA expression levels were detected in 60 surgically removed thyroid neoplastic and nonneoplastic samples and in 62 fine-needle aspiration (FNA) samples by RT-PCR using TaqMan MicroRNA Panel or individual miRNA sequence-specific primers. miRNA expression levels were calculated relative to normal thyroid tissue. All tumors were genotyped for most common mutations.
Results: Various histopathological types of thyroid tumors, including those deriving from the same cell type, showed significantly different profiles of miRNA expression. Oncocytic tumors, conventional follicular tumors, papillary carcinomas, and medullary carcinomas formed distinct clusters on the unsupervised hierarchical clustering analysis. Significant correlation between miRNA expression patterns and somatic mutations was observed in papillary carcinomas. A set of seven miRNAs (miR-187, miR-221, miR-222, miR-146b, miR-155, miR-224, and miR-197) that were most differentially overexpressed in thyroid tumors vs. hyperplastic nodules in the surgical samples was validated in the FNA samples, showing high accuracy of thyroid cancer detection.
Conclusions: In this study, we demonstrate that various histopathological types of thyroid tumors have distinct miRNA profiles, which further differ within the same tumor type, reflecting specific oncogenic mutations. A limited set of miRNAs can be used diagnostically with high accuracy to detect thyroid cancer in the surgical and preoperative FNA samples.
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