To report the long-term survival and late toxicity data of Stage III follicular lymphoma patients treated with primary radiotherapy.

Sixty-six patients with Stage III follicular small cleaved (FSC) or follicular mixed (FM) non-Hodgkin's lymphoma were treated with total lymphoid irradiation (61 patients) or whole body irradiation (5 patients) as their primary treatment modality from 1963 to 1982 at Stanford University. Adjuvant chemotherapy was given to 13 patients.

Median follow-up was 9.5 years with a range of 0.5-24.3 years. Median overall survival, cause-specific survival, freedom from relapse, and event-free survival were 9.5, 18.9, 7.1, and 5.1 years, respectively. Few initial relapses or lymphoma-related deaths were seen beyond the first decade of follow-up. Patient age and number of disease sites were the two strongest predictors of overall survival. The cohort of patients with limited Stage III disease demonstrated an 88% freedom from relapse and a 100% cause-specific survival with up to 23.5 years follow-up.

The long-term survival data for Stage III FSC or FM non-Hodgkin's lymphoma treated with primary radiotherapy are at least comparable and possibly better than results achieved with other therapeutic approaches. Patients with limited Stage III disease do particularly well. Whether these results are superior to an initial approach of deferred therapy until clinically indicated is currently unknown.