Impact on survival through consolidation radiotherapy for diffuse large B-cell lymphoma: a comprehensive meta-analysis.

Rituximab has improved response rates and overall survival in B-cell lymphoma (DLBCL). Radiotherapy is an effective treatment modality for lymphomas, but there is uncertainty on its use as consolidation after chemo-immunotherapy mainly in advanced stages. We evaluated its efficacy with a comprehensive meta-analysis and a systematic search of Pubmed, Embase, Cochrane, and abstracts from ASCO, ASH, ESMO and ASTRO published from June 1966 and December 2018. We identified 11 trials that evaluated consolidation radiotherapy following chemotherapy in a randomized fashion in 4'584 patients. The primary endpoint of this meta-analysis was PFS. As three of the eleven trials were retracted, this data is based on 2414 patients. For the primary endpoint (PFS), we found a hazard ratio (HR) of 0.77 (0.51 to 1.17, pooled (tau2: 0.25; I2: 85%), and a HR of 0.80 (0.53 to 1.21, pooled (bivariate meta-analysis). For overall survival, the HR is 0.93 (0.61 to 1.40; pooled (tau2: 0.25; I2: 74%) and 0.86 (0.58 to 1.27) in a bivariate meta-analysis. The lack of benefit did not change over time (p-value: 0.95 (tau2: 0.32; I2: 88%), and was also absent for PFS when stratifying for chemotherapy, the use of Rituximab, age, the dose of radiotherapy, application to patients in complete remission and with bulky disease. None of the trials used a PET-guided approach. This meta-analysis revealed no survival benefit when consolidation radiotherapy is given to unselected DLBCL patients following chemotherapy. These results need to be considered in future trials in the PET-CT era.