Impact of Primary Disease Site of Involvement by Early-Stage Follicular Lymphoma on Patient Outcomes

Follicular lymphoma is a common non-Hodgkin lymphoma that can start in a diverse array of tissues throughout the body. While the majority of patients may be able to live many years with this disease, cure remains very difficult to achieve. We sought to investigate the impact of follicular lymphoma primary disease site in early-stage disase on patient outcomes using a large national databse. Baseline demographic and disease data for patients diagnosed with follicular lymphoma from 2000-2015 was identified and extracted from the NCI Surveillance, Epidemiology, and End Results (SEER) database. Primary disease sites were grouped into one of two cohorts: nodal disease (lymph nodes and spleen) and extranodal disease (everything else). Analysis was performed using summary statistics, Kaplan-Meier method, and Cox-proportional hazards models for univariate and multivariate analysis. A total of 13,400 patients were included in the final analysis and the majority were non-Hispanic white (81%), with stage I (63%), and nodal FL (79%). Median overall survival for nodal disease was 15.1 years [95% CI (14.6-15.6)] while median overall survival for extranodal disease was 15.8 years [95% CI (14.9-16.3)]. Overall survival was slightly better for patients with extranodal disease [HR=0.89, 95% CI (0.84-0.96); p-value =0.00012]. This finding remained consistent after controlling for age and race [HR=0.84, 95% CI (0.79-0.90); p-value <0.0001]. The primary site of involvement by early-stage follicular lymphoma may have an impact on patient outcomes and warrants further investigation.MicroAbstract: This study investigated early-stage follicular lymphoma patient outcomes and disease characteristics using a national cancer database. Nodal early-stage follicular lymphoma may have worse outcomes compared to extranodal disease. Primary disease site may be a prognostication factor to further investigate for clinical application.