Sociodemographic Factors and Treatment Patterns Associated with Overall Survival in Splenic Marginal Zone Lymphoma: A Nationwide Retrospective Cohort Study (2000-2022)

Background: Splenic marginal zone lymphoma (SMZL) is a rare indolent lymphoma with extremely limited population level evidence on social and treatment correlates of survival. Methods: We conducted a retrospective cohort study using SEER (2000 to 2022) to evaluate OS in primary SMZL (ICD O 3 9689; spleen C42.2). We summarized baseline features and treatments and used Kaplan Meier and Cox regression. Results: The cohort included 3,548 patients (mean age 68.2 years; 53.6% female). Most were White (89.8%) and non Hispanic (92.1%). Ann Arbor stage was missing or blank in 39.4%. Initial therapy included chemotherapy in 26.4%, beam radiation in 0.7%, and primary site surgery in 21.4%. At last follow up, 56.8% were alive; non Hodgkin lymphoma accounted for 15.8% of the full cohort, with substantial competing causes including heart disease (6.1%). In multivariable Cox analysis, OS was independently associated with age (HR 1.073 per year, 95% CI 1.067 to 1.079), male sex (HR 1.337, 95% CI 1.203 to 1.486), Hispanic ethnicity (HR 1.426, 95% CI 1.194 to 1.703), chemotherapy (HR 1.246, 95% CI 1.118 to 1.390), year of diagnosis (HR 0.983 per category, 95% CI 0.973 to 0.993), marital status (married vs divorced HR 0.720, 95% CI 0.600 to 0.863), and race (Asian or Pacific Islander vs White HR 3.210, 95% CI 1.164 to 8.853). Conclusions: In our large population based analysis, OS in SMZL tracks with demographic and social variables and competing risks. Stage missingness and treatment selection limit causal inference for management effects.