Although cancer patients are known to experience mental disorders and face suicide risk, little is known about the relationship between mental illness and death by suicide in this group. As such, this study aims to examine the association between mental disorders and suicide risk among cancer patients. We used nationally representative cohort data, and included newly diagnosed cancer patients from 2004 to 2012 with whom we followed-up throughout 2013. We used the clinical diagnoses of all mental disorders as an independent variable and suicide death as a dependent variable to estimate the adjusted hazard ratio (AHR) of suicide deaths in patients with cancer using a Cox proportional hazard model. Among total cancer patients (n = 36,220), the 10,567 patients with mental disorders showed higher suicide risk than non-cancer patients (AHR, 1.53; 95% confidence interval [CI], 1.07-2.17), particularly in those who experienced mental disorders prior to cancer diagnosis (AHR, 2.24; 95% CI, 1.35-3.71). Suicide risk among cancer patients who had mood disorders (AHR, 2.23, 95% CI, 1.31-3.81) or anxiety and somatoform disorders (AHR, 1.61, 95% CI, 1.02-2.55) was higher than for those without mental disorders. Suicide risk of stomach (AHR, 3.32; 95% CI, 1.36-8.10) and liver (AHR, 7.57; 95% CI, 1.86-30.72) cancer patients who had mental disorders was higher than for patients without mental disorders. Cancer patients with mental disorders are at increased risk for suicide. During follow-ups after cancer diagnosis, early mental health support needs were provided to patients with mental disorders.
Keywords: Cancer; longitudinal cohort study; mental disorders; suicide.