Primary hepatopancreatobiliary lymphoma: epidemiology, clinical features, and treatment outcomes

Differences in the epidemiology, clinical features, and treatment strategies of primary lymphomas of the liver, pancreas, and biliary system (primary hepatopancreatobiliary lymphomas [PHPBL]) remain unclear. We compared the clinical characteristics of patients with lymphomas of these organ systems to facilitate earlier and more effective interventions. We retrospectively analyzed PHPBL data from the Surveillance, Epidemiology, and End Results (SEER) database (2000-2022). We compared the incidence rates, clinical indicators, and subtype distribution differences among the lymphoma subgroups. Propensity score matching (1:1) was applied to balance covariates between chemotherapy and non‑chemotherapy groups. Multivariate Cox regression models were used to identify prognostic factors. Kaplan-Meier survival analysis was performed. We included 2,509 patients with PHPBL. The overall PHPBL incidence showed a significant declining trend [annual percent change: -1.33%], most particularly for primary pancreatic lymphoma. Pathological type distribution varied across primary sites. Diffuse large B-cell lymphoma was most common in primary hepatic lymphoma, followed by follicular lymphoma in primary pancreatic lymphoma. Mucosa-associated lymphoid tissue (MALT) lymphoma most commonly involved the pancreas. Age, pathological type, primary site, SEER stage, marital status, and surgery or chemotherapy were independent prognostic factors. Subgroup multivariable analyses revealed that chemotherapy was independently associated with improved overall survival (OS) in both primary hepatic lymphoma (PHL) and primary biliary lymphoma (PBL), but cancer‑specific survival (CSS) benefit reached significance only in PHL. After propensity score matching, chemotherapy combined with surgery yielded the best survival outcomes in primary pancreatic lymphoma (PPL). Further analysis of surgery in PPL showed marked heterogeneity by histological subtype: surgery significantly improved OS in follicular lymphoma but not in other subtypes. This study revealed unique epidemiological patterns of PHPBL and emphasized the importance of individualized treatment based on pathological subtypes and primary sites. Chemotherapy should be particularly carefully selected in PHPBL.