Hypothyroidism after radiotherapy for primary thyroid lymphoma.

BACKGROUND Thyroid lymphoma is rare, with no standard therapeutic protocol. Radiotherapy is often employed. PATIENTS AND METHODS Nine patients who had received radiotherapy for thyroid lymphoma in our Institute, from September 2005 to August 2013, were reviewed for hypothyroidism. The median radiation dose was 40 Gy. Thyroid-stimulating hormone (TSH) levels were measured before and after radiotherapy, and hypothyroidism was defined as a TSH level exceeding 10 mIU/l. Peak TSH was defined as the highest TSH level during the follow-up period. RESULTS The complete response rate was 77.8%, and the 5-year overall survival rate was 74.1%. The median time-to-peak TSH was 162.5 days after the start of radiotherapy. Hypothyroidism was diagnosed in three (37.5%) out of eight patients without thyroidectomy. CONCLUSION Hypothyroidism is a frequent complication of radiotherapy for thyroid lymphoma.