Thyroid Cancer: Molecular Genetics

Abstract

Abstract Thyroid cancer is the most common malignancy of endocrine organs. The thyroid comprises two specialised cell types, follicular thyrocytes and C cells. Most thyroid cancers arise from thyroid follicular cells. These cancers include well‐differentiated papillary carcinoma and follicular carcinoma, poorly differentiated carcinoma and anaplastic carcinoma, whereas medullary carcinomas arise from the calcitonin‐producing C cells. Papillary and follicular carcinomas are the two most common types of thyroid cancer. Genetic alterations, including BRAF and RAS point mutations, and RET/PTC and PAX8/PPAR γ rearrangements, and p53 inactivation underlines the molecular mechanisms resulting in thyroid cancer. These genetic alterations are found in more than 70% of papillary and follicular thyroid carcinomas. The use of molecular markers is expected to improve the accuracy of diagnosis of thyroid cancers and inform the prognosis of each cancer. We review common genetic alterations in thyroid carcinomas and discuss the diagnostic and prognostic significance. Key Concepts: The thyroid cancers are subdivided into well‐differentiated papillary carcinoma and follicular carcinoma, poorly differentiated carcinoma, and anaplastic carcinoma. Papillary carcinomas carry point mutations of the BRAF and RAS genes as well as RET/PTC and TRK rearrangement. Follicular carcinomas carry either RAS mutations or PAX8/PPAR γ rearrangement. The knowledge of molecular genetics of thyroid cancer eventually getting the clinical impact, such as improvement of diagnostic accuracy, management of thyroid cancer, and surgical planning and can be a prognostic markers.