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 <0.01). Interaction analysis showed that Black patients with pre-existing MHD had worse survival outcomes compared with non-Black patients; mOS 30 mos vs. 51 mos (HR 3.2, 95% CI 1.6 - 6.7, p=0.035). Conclusions: Black patients with CRC and pre-existing MHD experienced significantly worse survival. There is an urgent need for integrated oncology with mental health services, particularly among racial minorities. Future prospective studies to mitigate these survival gaps are needed.