The current standard therapy for patients with diffuse large B-cell lymphoma (DLBCL) is rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP). The role of consolidative radiation therapy (RT) in the setting of R-CHOP chemotherapy is not well reported. This retrospective analysis is an attempt to clarify this role.

Subjects were 469 patients with histologically confirmed DLBCL treated between January 2001 and December 2007. Variables including age, sex, Ann Arbor disease stage, bulky disease status, standardized uptake values (SUVs) on positron emission tomography (PET), International Prognostic Index (IPI), and Ki67 staining (proliferation).

Of 469 patients, 190 (40.5%) had stage I or II disease and 279 (59.5%) had stage III or IV disease, 327 (70%) had at least six cycles of R-CHOP, and 142 (30.2%) had involved-field RT (dose, 30 to 39.6 Gy) after complete response to chemotherapy. Median follow-up was 36 months (range, 8 to 85 months). Multivariate analysis showed that RT (P < .0001), IPI score (P = .001), response to therapy (P = .001), use of six to eight cycles of R-CHOP (P < .001), and combined presence (P = .006) or absence (P = .025) of high Ki67, high PET SUV, and bulky disease influenced overall survival (OS) and progression-free survival (PFS). Matched-pair analyses of patients who received six to eight cycles of R-CHOP with stage I or II disease (44 pairs) and all stages (74 pairs) indicated that RT improved OS (hazard ratio [HR], 0.52 and 0.29, respectively) and PFS (HR, 0.45 and 0.24, respectively) compared with no RT.

This study showed significant improvements in OS and PFS among patients who received consolidation RT after R-CHOP chemotherapy for DLBCL.