Abstract 3820: Impact of primary site in early-stage follicular lymphoma on patient outcomes: Analysis of a large national database

Abstract Introduction: Follicular lymphoma (FL) is the most common indolent Non-Hodgkin lymphoma and is associated with better outcomes compared to other types of lymphoma. Despite this, cure is usually elusive and most patients experience multiple relapses within their lifetime. Previous studies have identified risk factors associated with worse outcomes, but little is known about the role of primary disease site in FL. We sought to investigate the outcomes of patients with extranodal early-stage FL compared to nodal disease using a large national cancer database. Methods: The Surveillance, Epidemiology, and End Results (SEER) public database was used to identify and extract data for patients with FL. Early-stage disease was defined as stage I or II by the Ann Arbor staging system. Most patients in the database were diagnosed after 2000 so this was used as the diagnosis year cutoff and also to reflect the impact of recent management strategies on outcomes. Patients were divided into two groups based on their primary disease site. These two groups were nodal (includes spleen) and extranodal. Treatment effect (surgery, radiation, or chemotherapy) was analyzed when available. Survival was estimated using the Kaplan-Meier method and compared using log-rank tests. Cox proportional hazards models were used for adjusted survival analyses. Results: A total of 13, 400 patients with FL of all histologic grades diagnosed between 2000 and 2015 were identified in the SEER database. The median age at diagnosis was 65 years (2-100). A majority of patients were Caucasian (81%), had stage I disease (62%), and belonged to the nodal FL group (79%). Median overall survival (OS) for patients with nodal FL was 181 months 95% CI (175-187). Median OS for extranodal FL was 189 months 95% CI (179-195). Extranodal FL was associated with better OS compared to the nodal group HR=0. 89, 95% CI (0. 84-0. 96) ; p-value =0. 00012 even after adjusting for age and race HR=0. 84, 95% CI (0. 79-0. 90) ; p-value 0. 0001. Conclusions: In this analysis of a large national cancer database, early-stage FL presenting as extranodal disease can be seen in about 20% of patients and is associated with slightly better outcomes. Citation Format: Olivia Davis, Rana Kasht, Andrew Cohoon, Silas Day, Sami Ibrahimi, Adam Asch, Taha Al-Juhaishi. Impact of primary site in early-stage follicular lymphoma on patient outcomes: Analysis of a large national database abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 3820.