A retrospective review was conducted of patients treated for thyroid non-Hodgkin's lymphoma (TNHL) at the Royal Marsden Hospital between 1936 and 1996 to determine the effect of radiotherapy (RT) on outcome. 91 patients were identified from the Thyroid Unit Database. There were 77 females and 14 males with a median age of 65 years (range 22-87 years). RT was delivered according to two separate policies: (1) involved field radiotherapy (IFRT) to the thyroid bed and cervical lymph nodes; (2) extended field radiotherapy (EFRT) covering the thyroid bed, cervical and mediastinal lymph nodes. 89 patients received RT as part of definitive treatment following surgery, to a dose of approximately 40 Gy. 25 patients received IFRT and 64 patients EFRT. 27 patients received cytotoxic chemotherapy. 18 patients (72%) treated with IFRT died of TNHL with a median relapse free survival (RFS) of 10 months and a median overall survival (OS) of 21 months. In contrast, only 29 patients (46%) treated with EFRT died of TNHL with a median RFS of 76 months (p = 0.01 for RFS with respect to IFRT and p = 0.04 for OS). Significantly more patients treated with IFRT relapsed locally (52% vs 27%). There was no difference in the rates of systemic relapse (20% vs 22%). EFRT alone for Stage I, but not for Stage II disease, yielded acceptable rates of local control and disease free survival with doses of at least 40 Gy. These historical data strongly support the addition of combination chemotherapy to the treatment regimen in all patients with Stage II disease. Indeed, in recent years this has become the standard of care for all cases of thyroid lymphoma unless the histology is of marginal zone type (mucosa associated lymphoma tissue (MALT) lymphoma).
