@article {JIN1359, author = {MICHAEL C. JIN and Z. JASON QIAN and UCHECHUKWU C. MEGWALU}, title = {Risk of Second Primary Malignancies After External Beam Radiotherapy for Thyroid Cancer}, volume = {42}, number = {3}, pages = {1359--1365}, year = {2022}, doi = {10.21873/anticanres.15605}, publisher = {International Institute of Anticancer Research}, abstract = {Aim: To investigate the association between external beam radiotherapy (EBRT) and the incidence of second primary tumors in patients with thyroid cancer. Materials and Methods: Data were extracted from the Surveillance, Epidemiology, and End Results 9 database. The study cohort included patients diagnosed with thyroid cancer between 1973 and 2017. Risk factors for second primary malignancies were identified with Cox proportional hazards models. Propensity score-matched analyses were used to assess the association between EBRT and second primary malignancies. Results: Out of 72,392 patients with thyroid cancer, 7,684 (10.6\%) developed a subsequent primary malignancy. Propensity score-matched analysis demonstrated patients receiving EBRT were more likely to develop second primary malignancies [30-year cumulative incidence=35.3\% (95\% confidence interval (CI)=30.4-39.8\% vs. 28.1\% (95\% CI=27.0-29.2\%); hazard ratio=1.17 (95\% CI=1.03-1.33)]. Conclusion: In patients with thyroid cancer, EBRT is associated with an increased incidence of second primary malignancies.}, issn = {0250-7005}, URL = {https://ar.iiarjournals.org/content/42/3/1359}, eprint = {https://ar.iiarjournals.org/content/42/3/1359.full.pdf}, journal = {Anticancer Research} }