Background: The strategy to apply involved-field radiotherapy (IF-RT) after immunochemotherapy in patients with bulky follicular lymphoma (FL) remains controversial.
Patients and methods: To evaluate the benefit of consolidating IF-RT, we retrospectively analysed relapse patterns and survival of patients with bulky FL. All patients were treated within a multicenter prospective randomized trial on 126 patients with one, three or six cycles Rituximab and six cycles CHOP. According to the protocol, patients presenting with bulky disease were to undergo consolidating IF-RT after immunochemotherapy. Forty-two eligible patients with bulky disease were identified, of which 26 were irradiated and 16 were not, contrary to the demand of the protocol.
Results: There was no significant difference between the irradiated and the non-irradiated group regarding presenting characteristics (P > 0.05). After a median follow-up of 60 months, 21 patients relapsed. In the irradiated group, relapse occurred in 12 of 26 patients. Fifty percent of relapses were located within the original bulk or within the bulk plus a new location. In the non-irradiated group, 9 of 16 patients relapsed. There was no statistically significant difference between exposure to IF-RT and the likelihood of a relapse per se (P = 0.751) or at a specific location (P = 0.66). Six-yr-PFS- (P = 1.0) and OS-rates (P = 0.68) were 52% and 80% after IF-RT and 48% and 73% without IF-RT.
Conclusion: There was no difference in relapse rate, PFS and OS between patients treated with and without consolidating IF-RT. This is the first analysis of its kind conducted in the Rituximab era. However, these results are based on a relatively small cohort size and are derived from a retrospective analysis, with the limitations of such an analysis being well known.