ROLE OF MOLECULAR MARKERS IN THYROID NODULE MANAGEMENT: THEN AND NOW.

OBJECTIVE: To describe the evolution and clinical utility of molecular testing for thyroid nodules and cancer achieved over the last 2 decades.
METHODS: Scientific reports on thyroid cancer genetics and molecular diagnostics in thyroid nodules.
RESULTS: 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.
CONCLUSION: 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. ABBREVIATIONS: 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.