Radiotherapy after immunochemotherapy improves outcomes in patients with primary mediastinal large B‐cell lymphoma

Abstract Objective Primary mediastinal B‐cell lymphoma is a rare and unique type of non‐Hodgkin's lymphoma that develops more frequently in younger patients and women. The combination of immunochemotherapy and radiotherapy (RT) has been suggested as the primary treatment choice. However, no consensus has been reached. Thus, we carried out an open‐label clinical trial. Patients with complete response after six cycles of immunochemotherapy were randomized to receive or not receive RT (control group). Methods From July 2004 to December 2012, 324 patients with primary mediastinal B‐cell lymphoma were enrolled and randomized at 1:1, with 164 and 160 patients in the RT and control groups, respectively. Results The 5‐year progression‐free survival was 84% (95% confidence interval [CI] 77–89%) in the RT group and 67% (95% CI 60–76%) in the control group ( P < 0.01). The 5‐year overall survival was 86% (95% CI 79–96%) in the RT group and 68% (95% CI 60%–74%) in the control group ( P < 0.01). Toxicity was minimal and well controlled. No late toxicities were observed. Conclusion RT as adjuvant treatment in patients with complete response after six cycles of immunochemotherapy improved the progression‐free survival and overall survival with minimal toxicities.