Role of radiotherapy in diffuse large B‐cell lymphoma in advanced stages on complete response after administration of cyclophosphamide, doxorubicin, vincristine, prednisone, and rituximab

Objective The role of radiotherapy (RT) as adjuvant therapy in patients with diffuse large B‐cell lymphoma and nodal bulky disease at diagnosis remains unclear. Thus, we carried out an open‐label clinical trial to assess if RT in patients with complete response after immunochemotherapy (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) improves progression‐free survival and overall survival. Methods Patients with complete response after six cycles of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone were randomly assigned to receive RT (involved field, 30 Gy) at sites of nodal bulky disease (tumor size >10 cm) as adjuvant treatment. Results Between June 2006 and December 2010, 258 patients were included in the study; 127 received RT and 131 did not receive RT (control group). The actuarial curves showed a 5‐year progression‐free survival of 87% (95% confidence interval [CI] 76–97%) in the RT group, which was significantly different from that in the control group, which was 45% (95% CI 32–60%) ( P  < 0.001). Furthermore, overall survival in the RT group was significantly better than that in the control group (91% [95% CI 84–99%] vs 59% [95% CI 52–66%]; P  < 0.001). RT was well tolerated. Acute toxicity was mild, and late toxicities were not noted. Conclusions RT in patients with complete response and nodal bulky nodal disease improved progression‐free survival and overall survival, with minimal toxicity. Thus, adjuvant RT should be considered as part of the initial treatment in this patient setting, even in the rituximab era.