Molecular testing for thyroid nodules: Review and current state.

Thyroid nodules affect nearly two-thirds of the world population. Fine-needle biopsy with cytologic evaluation remains the diagnostic test of choice to distinguish benign from malignant thyroid nodules yet fails to discriminate as benign or malignant in up to one-third of cases. This review discusses the limitation of current cytopathologic evaluation, the development of thyroid molecular testing, and the strengths and limitations of commercially available tests. Initial cytomolecular testing sought to identify specific gene mutations associated with thyroid cancer. Although the presence of a mutation was strongly associated with cancer, the likelihood of identifying a mutation was low; therefore, the test had low sensitivity. Subsequent tests developed have sought to improve the accuracy of cytomolecular testing for thyroid fine-needle aspirations, both to reassure patients and providers when malignancy may be absent and to confirm the malignancy when present. The development of cytomolecular testing for thyroid nodules has informed and improved current understanding of thyroid nodule formation and progression. When used appropriately and with clear understanding of the advantages and disadvantages, cytomolecular testing has the potential to improve patient care in the setting of indeterminate thyroid nodules by helping to guide both the need for and the extent of thyroid surgery. Cancer 2018;124:888-98.