Are Higher Doses of Consolidation Radiation Therapy Necessary in Diffuse Large B-cell Lymphoma Involving Osseous Sites?

AbstractPurposeThis study aimed to evaluate whether higher doses of consolidation radiation therapy (RT), which have been traditionally recommended for osseous sites in diffuse large B-cell lymphoma (DLBCL), are still necessary.Methods and materialsPatients with DLBCL with osseous involvement treated with first-line chemotherapy followed by consolidation RT between 1995 and 2016 were reviewed. The primary endpoint was 5-year freedom from local recurrence, estimated using the Kaplan-Meier method. Outcomes based on the RT dose received were also assessed.ResultsA total of 51 patients were identified. The most common chemotherapy regimens were rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (80%) and cyclophosphamide, doxorubicin, vincristine, and prednisone (12%) with a median of 6 cycles (range, 3-8 cycles). After chemotherapy, 82% of patients achieved a complete response (CR), and 18% achieved a partial response (PR). All patients in PR were deemed appropriate for consolidation RT. The median dose was 29 Gy (24 Gy for CR; 36 Gy for PR). After a median follow-up of 86 months, 8 patients relapsed, with 2 relapses in the RT field after consolidation RT of 30 and 39.6 Gy, respectively. Overall, the 5-year freedom from local recurrence was 96% (95% confidence interval [CI], 91%-100%), disease-free survival was 76% (95% CI, 65%-89%), and overall survival was 86% (95% CI, 76%-96%). No dose-response relationship was observed.ConclusionsIn patients with DLBCL with osseous involvement who achieved a CR after first-line chemotherapy, 20 to 30 Gy of consolidation RT led to high rates of local control. Higher doses should be reserved for patients in PR.