Favorable outcome of primary mediastinal large B-cell lymphoma patients treated with sequential RCHOP-RICE regimen without radiotherapy.

Abstract

Outcomes in primary mediastinal B cell lymphoma (PMBL) improved with the introduction of dose intense treatments, consolidation radiotherapy and rituximab. DA-EPOCH-R, which omits radiotherapy has been adopted with worldwide enthusiasm, despite lack of proven superiority in randomized trials. We aimed to evaluate the course and outcome of PMBL using an alternative intensive rituximab-containing regimen, RCHOP-RICE. We also evaluated the prognostic value of (18)FDG-PET-CT (PET-CT). We reviewed the clinical, laboratory and imaging data of PMBL patients receiving 1st-line treatment in Hadassah Medical Center between 8/2002 and 10/2014. Of 47 PMBL patients, 24 (51%) were treated with RCHOP-RICE and 23 (49%) with other protocols. Overall, the 5-year progression-free survival was 93% and the overall survival was 98% (87 and 100%, respectively, for the RCHOP-RICE regimen). Patient characteristics and treatment toxicities were balanced among protocols. A mean of 11.1±1.3 hospitalization days/patient were needed to administer RCHOP-RICE regimen compared to 37±2days/patient for DA-EPOCH-R (n=2). Radiotherapy was given to 3 patients (12%) treated with RCHOP-RICE compared to 18 patients (78%) treated with other protocols (p<0.01). For patients followed with interim and end of treatment (EOT) PET-CT, we observed a significant reduction in the uptake between the two (p<0.0001). Using a Deauville score cutoff of 3, the negative and positive predictive values (NPV and PPV) of EOT PET-CT were 94 and 33%, respectively. The RCHOP-RICE protocol results in excellent survival outcomes, generally permits omission of RT and is simpler to administer than DA-EPOCH-R. Interim PET-CT in PMBL may be unjustified; however, EOT Deauville scores ≤3 predicts a favorable outcome.