Clinical significance of B-Raf proto-oncogene, rat sarcoma virus oncogene homolog, and telomerase reverse transcriptase mutations in risk stratification and management of thyroid nodules: A large-scale cohort study

Objectives: B-Raf proto-oncogene ( BRAF) and telomerase reverse transcriptase ( TERT) mutations have established roles in the management of thyroid nodules, but rat sarcoma virus oncogene homolog ( RAS) mutations’ significance is less conclusive. Integrating mutation profiles with cytological grades provides evidence to evaluate the clinical significance of molecular testing in risk stratification and diagnosis of thyroid nodules. Material and Methods: A total of 5378 nodules were subjected to fine-needle aspiration (FNA cohort) and classified according to the Bethesda system for reporting thyroid cytology. Of them, 705 were surgically removed (thyroidectomy cohort) and pathologically examined, and 53 were followed for 0.5–53.6 months (follow-up cohort) and underwent at least one follow-up FNA. Eight follow-up nodules were resected. All FNA samples were tested for mutations of the BRAF V600E , TERT , and RAS genes. Results: 640 nodules of the thyroidectomy cohort and 6 follow-up nodules were malignant. Molecular testing showed BRAF V600E had a prevalence of 41.5, 58.0, and 15.1% in FNA-, thyroidectomy-, and follow-up cohorts, respectively, but RAS mutations’ prevalence was no higher than 4% in any of them, while TERT mutations’ prevalence was <1%. Consistently, BRAF V600E had a sensitivity of 63.9% and a specificity of 100% in diagnosing malignancy in the thyroidectomy cohort, while RAS mutations had much lower sensitivity and specificity (1.88 and 7.65%, respectively). Furthermore, BRAF V600E increased the risk of malignancy of the FNA cohort to 100% regardless of cytological grades, while RAS mutations showed no increase. In the follow-up nodules, BRAF V600E was strongly associated with malignancy and elevated cytological grades, while RAS mutations showed no association. Conclusion: BRAF V600E is a robust marker for thyroid malignancy in FNA specimens, whereas RAS mutations have limited standalone diagnostic utility but may still provide adjunctive value for risk stratification when interpreted together with cytology and clinical findings.