Background: Research suggests mental illness contributes to poor survival among cancer patients. In New York State (NYS), Medicaid is the largest single insurer for individuals with mental illness. We investigated the influence of preexisting mental illness on all-cause and cause-specific mortality among Medicaid-insured women diagnosed with breast cancer. Methods: 9,479 women aged <65 years diagnosed with breast cancer and reported to the NYS Cancer Registry from 2004-2016 were linked with NYS Medicaid claims. Women were grouped as having depression or severe mental illness if they had at least three diagnosis claims for mental illness with at least one claim within three years prior to breast cancer diagnosis. Severe mental illness included schizophrenia, bipolar disorder, and other psychotic disorders. Hazard ratios (HR) and 95% confidence intervals (95% CI) were calculated with Cox regression, adjusting for potential confounders. Results: Women with severe mental illness had greater risks of all-cause (HR 1.49; 95% CI 1.25, 1.78), cancer (HR 1.36; 95% CI 1.09, 1.68), and cardiovascular (HR 2.14; 95% CI 1.22, 3.74) mortality compared to women without mental illness. No association was observed for depression. The association between severe mental illness and all-cause mortality was strongest among Asians (HR 3.85; 95% CI 1.55, 9.60) but also observed in White (HR 1.50; 95% CI 1.17, 1.93) and Black (HR 1.36; 95% CI 1.02, 1.80) women. Additionally, associations were also observed among obese (HR 1.83; 95% CI 1.42, 2.36) and postmenopausal (HR 1.64; 95% CI 1.35, 2.01) women with preexisting severe mental illness, but no association was observed for premenopausal women. Conclusion: Women with preexisting severe mental illness diagnosed with breast cancer have an elevated mortality risk and should be monitored and treated by a coordinated cross-functional clinical team.

Citation Format: Wayne R Lawrence, Akiko Hosler, Margaret Gates, Matthew Leinung, Xiuling Zhang, Wangjian Zhang, Maria Schymura, Francis Boscoe. Preexisting mental illness on all-cause and cause-specific mortality among Medicaid-insured women diagnosed with breast cancer [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr A106.