Efficacy of radiotherapy in primary mediastinal diffuse large B-cell lymphoma: a systematic review and meta-analysis of 1,392 patients.

Primary mediastinal B-cell lymphoma (PMBCL) patients who achieve a complete response (CR) following first-line immunochemotherapy tend to have favorable outcomes, even without subsequent radiotherapy (RT). However, it remains unclear whether the survival of patients who do not achieve CR after first-line therapy and subsequently receive radiotherapy is comparable to that of CR patients who undergo observation alone. To address this gap, we conducted a systematic review and meta-analysis to compare progression-free survival (PFS) and overall survival (OS) between CR patients who forgo radiotherapy and non-CR patients who receive consolidative radiotherapy. Additionally, we examined potential influencing factors to provide evidence-based guidance for clinical treatment strategies. A comprehensive search of multiple databases (PubMed, EMBASE, and Cochrane Library) was conducted for the period from January 1, 2012, to September 1, 2024. Using predefined keywords and screening procedures, 15 studies were ultimately included. The primary endpoint was PFS, with OS as a secondary endpoint. Subgroup analyses were performed based on chemotherapy regimens. This systematic review and meta-analysis of 15 studies demonstrated that consolidative radiotherapy significantly improves PFS in patients with partial remission (PR) after first-line immunochemotherapy, with an overall risk ratio (RR) of 1.11 (95% confidence interval [CI]: 1.05-1.16). For OS, the RR was 1.04 (95% CI: 0.97-1.12), crossing the line of no effect, which suggests that consolidative radiotherapy does not have a statistically significant impact on OS. Consolidative radiotherapy improves PFS in patients with PMBCL, but its effect on OS is not statistically significant.