R-CHOP: Does One Size Fit All in Diffuse Large B Cell Lymphoma?

with or without histiocytes [7] . Clinically, THRBCL has historically been observed to occur at a younger age than traditional DLBCLs, and with a tendency to present at an advanced stage with preferential involvement of the spleen, liver and bone marrow. Prior to rituximab, patients with THRBCL appeared to have similar prognoses as their stage-matched DLBCL counterparts. Does this hold true in the rituximab era? Kim et al. [6] report their matched-pair analysis comparing outcomes between THRBCL and DLBCL patients treated with R-CHOP. Among 11 patients with THRBCL and 33 patients with DLBCL, they find complete response rates of 91 and 97%, respectively, with both groups having an excellent 3-year event-free survival of 81%. Though this study is clearly too small to definitively answer this question, it does offer the first glimpse at THRBCL outcomes with R-CHOP in the modern era, and encouragingly suggests that the benefits or R-CHOP in DLBCL can be extrapolated to the THRBCL variant. Studies including larger numbers of patients to validate this finding would be helpful. Ongoing questions remain about whether R-CHOP has been established as the standard of care in other subsets of DLBCL. PMBCL is a distinct clinical variant of DLBCL occurring primarily in young patients with a median age in the thirties and presenting predominantly with bulky limited-stage disease in the mediastinum. This disease has historically demonstrated an increased rate of chemotherapy resistance compared to DLBCL, necessiR-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone) has justly emerged as the standard of care for the treatment of diffuse large B cell lymphoma (DLBCL) based on three large randomized clinical trials all showing improved overall survival compared to CHOP alone [1–3] . Two additional studies have assessed whether R-CHOP given every 14 days would improve outcomes compared to the traditional 21-day schedule, each showing no incremental benefit to dosedense administration [4, 5] . So R-CHOP on a 21-day cycle is the optimal treatment for all patients with DLBCL. Or is it? DLCBL is a heterogeneous disease including diverse variants such as T cell histiocyte rich B cell lymphoma (THRBCL), primary mediastinal B cell lymphoma (PMBCL), and the molecular subtypes germinal center-like DLBCL and activated B cell-like (ABC) DLBCL, among others. Certain subsets of DLBCL may not have been included in sufficient numbers in randomized trials to date to fully un derstand whether the results observed in DLBCL as a whole can be broadly applied to less common DLBCL variants. In this issue of Acta Haematologica , Kim et al. [6] seek to address this question spe cifically for THRBCL, an uncommon morphologic variant of DLBCL. Pathologically, THRBCL is distinguished from traditional cases of DLBCL based on the paucity of large malignant B cells surrounded by an inflammatory microenvironment composed predominantly of polyclonal T lymphocytes, Received: August 26, 2013 Accepted after revision: August 28, 2013 Published online: November 1, 2013