RACIAL DIFFERENCES AND COMPARATIVE EFFECTIVENESS OF RITUXIMABBASED THERAPIES AMONG ELDERLY FOLLICULAR LYMPHOMA (FL) PATIENTS – A RETROSPECTIVE COHORT STUDY USING SEER-MEDICARE LINKED DATABASE

OBJECTIVES: Follicular Lymphoma (FL) is the most common indolent lymphoma (15,000 cases diagnosed in US, 2016). Limited evidence exists on racial differences in treatment and the comparative effectiveness of rituximab-based chemo/ immunotherapy treatment regimens among elderly FL patients. Herein, we examined the differences in treatment utilization for elderly FL patients stratified by race and characterized the comparative effectiveness of treatments on cancerspecific and all-cause mortality. METHODS: We conducted a retrospective cohort study of patients (age > 66 years) diagnosed with first primary FL from 2001-2011, using the SEER-Medicare database. Differences in risk of all-cause and cancer-specific mortality by race were examined using Cox proportional hazards models. Adjusted hazard ratios and 95% CIs were also estimated to determine the comparative effectiveness of rituximab-based chemotherapy versus observation only. RESULTS: Among 4,849 elderly FL patients, treated patients tended to be younger than patients receiving observation only. African-American patients were less likely (44%) to receive treatment versus Caucasian patients (53%). Our findings suggested benefit of rituximab-based chemo/immunotherapy across all races, although only statistically significant for Caucasian patients, for cancer-specific mortality (Caucasian: HR=0.55, 95% CI:0.44-0.68; African-American: HR=0.62, 95% CI:0.30-1.41; Hispanic: HR=0.69, 95% CI:0.42-1.28; Asian/Pacific Islander : HR=0.65, 95% CLO.27-1.40) and all-cause mortality (Caucasian: HR=0.53, 95% CI: 0.46-0.62; African-American: HR=0.61, 95% CI:0.28-1.93; Hispanic: HR=0.51, 95% CI:0.23-1.10; Asian/Pacific Islander : HR=0.54, 95% CI:0.20-0.94). Further subgroup analyses suggested similar benefits of rituximab plus chemotherapy and rituximab monotherapy when compared to observation (log-rank p