Abstract 6635: Evaluation of stage IV PTCL, NOS of the liver and gastrointestinal tract using a large national cancer database.

Abstract Introduction: Peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS) is a heterogeneous group of PTCL for which extranodal involvement is common and outcomes are poor. Previous research has suggested that primary disease site may impact overall survival (OS) for early-stage PTCL, NOS with worse outcomes for patients with gastrointestinal/genitourinary involvement. Little is known about the role of primary disease site in advanced stage disease and the impact of discrete gastrointestinal organ involvement. The purpose of this study was to investigate outcomes for stage IV PTCL, NOS with extranodal involvement using a national cancer database. Methods: Patient and disease characteristics for individuals diagnosed with PTCL, NOS between 2000 and 2015 were extracted from the Surveillance, Epidemiology, and End Results (SEER) database. Patients with extranodal stage IV PTCL, NOS were isolated and included in the final analysis to reflect cases of extensive extranodal involvement. Primary disease sites were grouped into 11 distinct categories based on the most common primary sites identified. Our main primary disease sites of interest were liver and luminal GI tract, but other primary disease sites were analyzed as well with spleen serving as the comparison group. Patient and disease characteristics were analyzed using summary statistics. Survival analyses were performed using the Kaplan-Meier method and Cox proportional hazards models. Treatment status was identified for each case, and survival was compared between chemotherapy and non-chemotherapy groups for each primary disease site. Results: A total of 464 patients were included in the final analysis. Median age was 63.0 years. Most patients were non-Hispanic white (60.8%) or male (62.3%). Thirteen cases (2.8%) involved primary disease of the liver while 70 cases (15.1%) involved the GI tract. Median OS for stage IV PTCL, NOS involving the liver was 1 month (95% CI (0-4)]. Median OS for stage IV PTCL, NOS of the GI tract was 4 months 95% CI (3-5). Primary disease of the liver was associated with worse lymphoma-specific survival HR=2.400, 95% CI (1.081-5.328); p-value=0.0314. Primary disease of the GI tract was associated with worse lymphoma-specific survival HR=2.090, 95% CI (1.220-3.579); p-value=0.0073 and overall survival HR=1.797, 95% CI (1.121-2.881); p-value=0.0149. No statistically significant difference in overall survival or disease-specific survival was detected between treatment groups for PTCL, NOS of the liver HR=0.780, 95% CI (0.185-3.287); p-value=0.7354. Conclusions: Stage IV PTCL, NOS of the luminal GI tract was associated with worse OS and disease-specific survival. Stage IV PTCL, NOS of the liver was associated with worse disease-specific survival and may be considered a chemotherapy-resistant compartment. Citation Format: Olivia Davis, Taha Al-Juhaishi, Ryan Wilcox. Evaluation of stage IV PTCL, NOS of the liver and gastrointestinal tract using a large national cancer database abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 6635.