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

Introduction: 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.

Objective: We sought to investigate the impact of follicular lymphoma primary disease site in early-stage disease on patient outcomes using a large national database.

Methods: 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.

Results: 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].

Conclusions: The primary site of involvement by early-stage follicular lymphoma may have an impact on patient outcomes and warrants further investigation.