Early Stage W.H.O. Grade I and II Follicular Lymphoma Treated with Radiation Therapy Alone

OBJECTIVES: This retrospective study was undertaken to evaluate the outcome of patients with stage I or II (limited stage), grade I–II follicular non-Hodgkin’s lymphoma (FL) treated with radiation therapy (RT) alone as initial management. METHODS: Patients with stage I or II and pathologically confirmed WHO grade I or II FL treated initially with RT alone between 1982 and 2008 were identified from a population based cancer registry. RESULTS: Forty patients with a mean age 61.3 years at diagnosis were identified. The median follow up was 6.9 years from the end of radiation therapy. Stage was I (n = 26) and II (n = 14). None had B symptoms. The Follicular Lymphoma International Prognostic Index (FLIPI) was low risk in 26 patients and intermediate risk in 5. Doses ranged from 15 Gy to 48 Gy, with a median dose of 35 Gy. All patients achieved a complete clinical response (CR). 5 and 10 year overall survival (OS) was 86% and 59%, progression free survival (PFS) 67% and 54%. Age ≥60 at diagnosis was associated with reduced OS, p = 0.029, but did not affect PFS. No other clinical features including grade or FLIPI were significant for outcomes. Local failure was uncommon occurring in 8% (3/40) although this was 21% (3/14) of all recurrences. CONCLUSIONS: OS and PFS outcomes for radiation alone in limited stage low grade FL patients from this single institution study are consistent with previously published data. No predictors were prognostic for PFS. A dose of ≤35 Gy may be appropriate. In this highly selected homogeneous group the FLIPI loses discriminating ability. Local control is excellent, and a majority of patients are free of disease after 5 years.