Racial differences in the impact of pre-existing mental health diagnosis on colorectal cancer survival: A single-center retrospective propensity-matched analysis.

45 Background: Racial disparities in colorectal cancer (CRC) epidemiology and mortality have been well documented, with Black patients having higher rates of late-stage presentations and worse survival outcomes. However, the differential impact of a pre-existing mental health diagnosis (MHD) on CRC outcomes across racial groups has not been well-studied. Methods: We conducted a retrospective study of patients with CRC treated at a major cancer center between 2015 and 2020. Patients with a documented MHD prior to their CRC diagnosis were included in the analysis. The cohort was further refined using 1:1 propensity score matching (PSM), performed to balance demographic and clinical confounders, including age, tumor site, cancer stage, insurance status, and tobacco use across Black and non-Black patients. Survival outcomes were assessed using Cox proportional hazards models, stratified by cancer stage and including an interaction term between race and pre-existing MHD. Statistical significance was set at 0.05. Results: Of 2,713 patients with CRC and non-missing race data (Black: 1,028; White/Other: 1,685), 2,056 were included in the analysis after PSM. Median age - 62 years, 52% were female, 80% had colon cancer, and 12% reported tobacco use. Stage distribution - I (21%), II (16.5%), III (27.3%), and IV (35%). Pre-existing MHD was present in 26/1028 (2.5%) of Black and 23/1028 (2.3%) of non-Black patients. Baseline characteristics were balanced between racial groups, though patients with pre-existing MHD were more often female or older (Table 1). Sex and age at diagnosis were included in proportional hazards models. Black race and pre-existing MHD were independently associated with shorter survival; mOS 55 mos for Black vs. 89 mos for non-Black patients (HR 1.50, 95% CI 1.3–1.7, p