Radiotherapy in stage I-III follicular non-Hodgkin lymphoma. Retrospective analysis of a series of 50 patients

The goal of this work was to analyze the response rate and outcome of patients with stage I-III follicular lymphoma (FL) treated with radiotherapy (RT) alone.

The records of 50 consecutive patients with stage I-III FL treated with RT alone at our department from 1988-2009 were analyzed. The median age was 60 years (range 32-80 years) with a median follow-up duration of 8 years (range 4-11 years). Clinical staging was performed according to the Ann Arbor system. Stage I: 30 patients (60%), stage II: 15 patients (30%), stage III: 5 patients (10%). Thirty-two patients (64%) presented with nodal disease, 14 patients (28%) presented with disease in extranodal sites, and 4 patients (8%) had nodal and extranodal involvement. The RT field encompassed only the involved Ann Arbor nodal regions (involved-field RT) in 26 patients (52%), mantle and whole abdominopelvic fields in 6 patients (12%), mantle field in 10 patients (20%), whole abdominopelvic fields in 5 patients (10%), and a so-called mini-mantle in 3 patients (6%). The total RT dose ranged from 26-56 Gy (median 40 Gy) in daily fractions of 1.2-2.5 Gy.

Complete remission (CR) and partial remission (PR) were observed in 39 (76%) and 9 (20%) patients, respectively. Only 2 of 8 patients (25%) with tumor bulk > 5 cm reached CR, whereas 37 of 42 patients (88%) with a maximum lymphoma diameter < 5 cm achieved CR (p = 0.0001). The median overall survival (OS) and median event-free survival (EFS) were 18 years (CI 95% 10-26 years) and 7 years (6-8 years), respectively. The 2-, 5-, and 10-year OS were 96 ± 3%, 90 ± 5%, and 70 ± 9%, respectively. The 2-, 5-, and 10-year EFS were 90 ± 5%, 70 ± 7%, and 38 ± 9%, respectively. Fifteen patients developed a recurrence outside the radiation field (30%) and 4 patients developed an in-field recurrence (8%). All in-field recurrences were observed in regions without clinical (macroscopic) involvement, which were irradiated with a dose of ≤ 26 Gy. Pretreatment maximum lymphoma diameter < 5 cm (p = 0.039) and complete remission after RT (p = 0.021) were significantly associated with a better OS in the univariate analysis.

RT is a curative option in the treatment of limited stage FL. If RT of microscopically uninvolved area is necessary, a reduction in the radiation dose should be carefully weighed against the risk of in-field recurrences.