Consolidative Radiotherapy to Residual Masses After Chemotherapy Is Associated With Improved Outcome in Diffuse Large B-Cell Lymphoma. A Retrospective, Population-Based Study

The role of radiotherapy (RT) in diffuse large B-cell lymphomas with advanced disease is unclear. In this retrospective study, 2 cooperating university hospitals in Western Norway had different practices in use of RT, but similar patient characteristics and chemotherapy. RT to a residual mass after chemotherapy, in low-intermediate risk groups with advanced disease, was associated with improved cancer-specific and overall survival. Background: The role of consolidative radiotherapy (RT) in advanced diffuse large B-cell lymphoma (DLBCL) is not established. Patients and Methods: In a population-based retrospective analysis of patients with DLBCL in Western Norway during 2003 to 2008, 170 consecutive patients admitted to Haukeland University Hospital (HUS) and 94 to Stavanger University Hospital (SUS) were included. The mean age was 64 years (range, 17-95 years), 147 patients (56%) were male, 80 patients (30%) had stage I/II, 126 patients (48%) stage III/IV, and 57 patients (22%) had primary extranodal disease. Results: There were no differences between hospitals in patient characteristics, use of rituximab, number of chemotherapy courses or cumulative doses, or in distribution of response categories after chemotherapy. The use of RT was significantly different: 17 patients (23%) received RT at SUS and 92 patients (65%) at HUS (P < .001). For 219 patients with International Prognostic Index (IPI) score of 0 to 3, 5-year cancer-specific survival (CSS) was 67% at SUS and 81% at HUS (P = .012). For 73 patients with complete response after chemotherapy there were no differences in survival between patients with and without RT. For 138 patients with any residual mass after chemotherapy, there were highly significant differences in favor of receiving RT (n = 81) versus no RT (n = 57): 5-year CSS 89% versus 69% (P < .001), and 5-year overall survival 82% versus 59% (P = .005). The effect of RT on residual mass was evident in most subgroups, mainly in low to intermediate risk, but not in high-risk (IPI 4-5) patients. Conclusion: With the limitations of a retrospective study, these data suggest that consolidative RT might improve survival in DLBCL patients with a residual mass after chemotherapy, also in advanced disease.