Treatment Selection and Survival Outcomes in Early-Stage Diffuse Large B-Cell Lymphoma: Do We Still Need Consolidative Radiotherapy?

Abstract

The choice between chemotherapy alone and chemotherapy plus consolidative radiotherapy (RT) for diffuse large B-cell lymphoma (DLBCL) remains controversial. We aimed to define factors affecting treatment selection and the resulting survival outcomes. Using the National Cancer Data Base, we identified 59,255 patients with stages I and II DLBCL treated with multiagent chemotherapy alone or chemotherapy plus consolidative RT between 1998 and 2012. Univariable and multivariable analyses were performed to identify sociodemographic, treatment, and tumor characteristics predictive of overall survival (OS) and treatment use. Propensity-adjusted Cox proportional hazard ratios for survival were used to account for indication bias. Of the 59,255 patients with DLBCL enrolled onto the study, 46% had stage II disease, 42% had extranodal disease, and 58% were more than 60 years of age. Only 39% received combined-modality therapy, and this proportion significantly declined from 47% in 2000 to 32% in 2012 (P < .001). Treatment selection was significantly influenced by race, comorbidity, insurance type, education quartile, facility type, age, stage, B symptoms, distance from treatment facility, and year of diagnosis. The median follow-up time was 60 months (interquartile range, 33 to 93). Estimated 5-year and 10-year OS rates were, respectively, 79% and 59% for all patients, 75% and 55% for patients receiving chemotherapy alone, and 82% and 64% for patients receiving combined-modality therapy (P < .001). Even after adjusting for immortal times and indication bias, combined-modality therapy was associated with better OS (HR, 0.66; 95% CI, 0.61 to 0.71; P < .001) than was chemotherapy alone. Use of consolidative RT after multiagent chemotherapy in DLBCL is decreasing in the modern era. Selection of treatment strategy is affected by both classical prognostic features and socioeconomic factors. Abandonment of combined-modality therapy in favor of chemotherapy alone negatively affects patient survival.