Clinical Outcomes in Patients With DLBCL Treated With R-CHOP According to Radiotherapy and Interim PET Response.

ABSTRACT

Background/Aim: Interim positron emission tomography/computed tomography (PET/CT) scan is a valuable tool for assessing the early metabolic response to chemotherapy in diffuse large B-cell lymphoma (DLBCL). Although radiotherapy is an effective treatment for lymphoma, especially for local tumor control, the role of consolidative radiotherapy in diffuse large B-cell lymphoma (DLBCL) remains controversial. This study analyzed the clinical outcomes of patients with DLBCL treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP), stratified by interim PET response and the administration of radiotherapy. Patients and Methods: We conducted a retrospective review of 107 patients with DLBCL treated with R-CHOP chemotherapy between January 2012 and December 2016. Overall survival (OS), recurrence-free survival (RFS), and freedom from disease progression (FFDP) were calculated using the Kaplan-Meier method and compared using the log-rank test. Results: Forty-six patients were included in this analysis, with a median follow-up time of 65.9 months (range=4.7-125.3 months). The metabolic CR (mCR) group exhibited superior OS, RFS, and FFDP compared with the metabolic PR (mPR) group (p=0.003, p=0.001, and p=0.008, respectively). The 1-, 2-, and 5-year FFDP were 92.97%, 89.3%, and 85.6%, respectively, in the mCR group and 78.6%, 61.9%, and 44.2%, respectively, in the mPR group. In subgroup analysis, the FFDP of the mPR group without radiotherapy was significantly lower than that of the other groups (mCR with/without radiotherapy and mPR with radiotherapy, p=0.001). Conclusion: Consolidative radiation therapy using interim PET can benefit patients who do not achieve mCR. Further well-controlled prospective randomized trials are required.