Abstract
Thyroid cancer (TC) is the most common endocrine malignancy worldwide, with an annual incidence of around 300,000 cases. In recent decades, the incidence of TC in many countries, including Saudi Arabia, has increased significantly. Genomics has allowed multiple mutations to be examined simultaneously across multiple genes, providing a detailed genomic profile for a given tumor. It is understood from a molecular perspective that different signaling pathways may have genetic abnormalities as the primary factors in thyroid tumorigenesis. While there is still early progress in the usage and standardization of targeted next-generation sequencing (NGS) in TC, a major ongoing study to distinguish malignant from benign thyroid nodules from fine-needle aspiration (FNA) has shown promising results that can prevent unnecessary surgery, based on NGS analyses of mutations and gene fusions associated with most TC. The differential diagnosis and malignancy risk stratification of TC require multidisciplinary skills and experience of both ultrasound and the FNA and molecular analysis. The most common TC mutations are point mutations in the BRAF and the chromosome rearrangements of RET/papillary TCs. The transition mechanisms tend to be linked to specific etiological features, which are very crucial while deciding the treatment protocol. On the other hand, FNA cytology has an intrinsic drawback. The findings of infinite cytology cannot differentiate some types of TC, such as follicular adenomas, thyroid follicular carcinomas, or papillary thyroid follicular. Nevertheless, accumulating evidence indicates that molecular diagnostic approaches can overcome these limitations. In this review, we present an updated summary, which focuses primarily on molecular alterations in the tumorigenesis and biomarker investigations of TC.

Key words: Thyroid cancer, molecular testing, gene panel, NGS, FNA, BRAF