R-CHOP versus dose-adjusted R-EPOCH in frontline management of primary mediastinal B-cell lymphoma: a multi-centre analysis.

Primary mediastinal (thymic) large B-cell lymphoma (PMBCL) is an uncommon subtype of non-Hodgkin lymphoma (NHL) that presents with a mediastinal mass and has unique clinicopathological features. Historically, patients with PMBCL were treated with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone) chemotherapy ± involved field radiation. Since a phase II trial, published in April 2013, demonstrated excellent results using dose-adjusted (DA) R-EPOCH (rituximab, etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin), this treatment has gained popularity. We performed a retrospective, multicentre analysis of patients aged ≥18 years with PMBCL since January 2011. Patients were stratified by frontline regimen, R-CHOP versus DA-R-EPOCH. 132 patients were identified from 11 contributing centres (56 R-CHOP and 76 DA-R-EPOCH). The primary outcome was overall survival. Secondary outcomes included progression-free survival, complete response (CR) rate, and rates of treatment-related complications. Demographic characteristics were similar in both groups. DA-R-EPOCH use increased after April 2013 (79% vs. 45%, P < 0·001), and there was less radiation use after DA-R-EPOCH (13% vs. 59%, P < 0·001). While CR rates were higher with DA-R-EPOCH (84% vs. 70%, P = 0·046), these patients were more likely to experience treatment-related toxicities. At 2 years, 89% of R-CHOP patients and 91% of DA-R-EPOCH patients were alive. To our knowledge, this represents the largest series comparing outcomes of R-CHOP to DA-R-EPOCH for PMBCL.