The effect of history of severe mental illness on mortality in colorectal cancer cases: a register-based cohort study.

Background: While the link between mental illness and cancer survival is well established, few studies have focused on colorectal cancer. We examined outcomes of colorectal cancer among persons with a history of severe mental illness (SMI).

Material And Methods: We identified patients with their first colorectal cancer diagnosis in 1990-2013 (n = 41,708) from the Finnish Cancer Registry, hospital admissions due to SMI preceding cancer diagnosis (n = 2382) from the Hospital Discharge Register and deaths from the Causes of Death statistics. Cox regression models were used to study the impact on SMI to mortality differences.

Results: We found excess colorectal cancer mortality among persons with a history of psychosis and with substance use disorder. When controlling for age, comorbidity, stage at presentation and treatment, excess mortality risk among men with a history of psychosis was 1.72 (1.46-2.04) and women 1.37 (1.20-1.57). Among men with substance use disorder, the excess risk was 1.22 (1.09-1.37).

Conclusion: Understanding factors contributing to excess mortality among persons with a history of psychosis or substance use requires more detailed clinical studies and studies of care processes among these vulnerable patient groups. Collaboration between patients, mental health care and oncological teams is needed to improve outcomes of care.