Outcomes of surgery and postoperative radiation therapy in managing medullary thyroid carcinoma

Background and Objectives We evaluated the outcomes of surgery with or without postoperative radiation therapy (PORT) in the management of medullary thyroid carcinoma (MTC). Methods From two tertiary cancer centers, 297 consecutive patients with MTC treated with PORT (n = 46) between 1990 and 2016 or surgery alone (n = 251) between 2000 and 2016 were reviewed. Results Ten-year cumulative incidences of locoregional and distant failure were 30.2% and 24.9% in the surgery cohort, and 16.9% and 55.2% in the PORT cohort. In the surgery alone cohort, T4 disease, extrathyroidal extension, N1 disease, extranodal extension (ENE), and residual disease after surgery were associated with local failure. The PORT cohort had significantly higher proportions of patients with T4 disease, N1 disease, ENE, and residual disease. Conclusions High-risk clinical features can help identify patients with MTC at high-risk for local failure after surgery alone. Patients with high-risk clinical features had effective locoregional control after PORT.