Early stage W.H.O. grade I and II follicular lymphoma treated with radiation therapy alone

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.

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.

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.

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.