Impact of the double expression of MYC and BCL2 on outcomes of localized primary gastric diffuse large B-cell lymphoma patients in the rituximab era

Abstract

Diffuse large B-cell lymphoma (DLBCL) is a common subtype of primary gastric lymphoma, accounting for 50–60% of cases. 1 Prior to the rituximab era, a Japanese phase II trial evaluated three courses of cyclophosphamide, doxorubicin, vincristine and prednisolone (CHOP), followed by 40.5 Gy of involved field radiotherapy (IFRT) for localized (stage I, II 1 based on the Lugano Staging System for Gastrointestinal Lymphoma 2 ) primary gastric DLBCL (PG-DLBCL) and the study yielded good therapeutic results. 3 Rituximab plus CHOP (R-CHOP) therapy has been shown to improve the prognosis of DLBCL patients over that of patients treated with CHOP. 4 , 5 The efficacy of three cycles of R-CHOP followed by IFRT for localized DLBCL was evaluated in a phase II trial by the Southwest Oncology Group and also showed favorable results. 6 On the basis of these findings, a rituximab-containing regimen, particularly three cycles of R-CHOP followed by IFRT, is regarded as one of the standard therapies for localized DLBCL including PG-DLBCL. Recent studies demonstrated that the double rearrangement (double hit) of the MYC and BCL2 genes and the double expression of the MYC and BCL2 proteins were associated with a poor prognosis for patients with nodal DLBCL. 7 , 8 , 9 , 10 However, the clinical impact of the double expression of MYC and BCL2 on PG-DLBCL remains unknown. We retrospectively analyzed patients with localized PG-DLBCL who were initially treated with a rituximab-containing regimen, with a focus on the status of MYC and BCL2.