Suicide after cancer diagnosis in South Korea: a population-based cohort study

Objective The present study aimed to determine whether the suicide risk increased after a cancer diagnosis. Design Population-based cohort study. Setting and participants This study incorporated the National Health Insurance Service-National Sample Cohort in South Korea. Of the 975 348 subjects, 39 027 with cancer and 936 321 who were cancer free participated between 2005 and 2013. Primary outcome measure Suicide. Results A total of 110 suicides (82 men, 28 women) were identified among these 39 027 subjects with cancer during a total of 127 184 person-years; among the 936 321 cancer-free subjects, 2163 suicides were reported during a total of 8 222 479 person-years. Cox proportional hazards models were used to compare all-cause and suicide mortalities after cancer diagnosis following adjustment for possible confounding covariates. After adjusting for factors related to suicide, we identified an elevated relative risk of suicide among patients with cancer (HR: 1.480, 95% CI: 1.209 to 1.812). Among men, the relative risk was substantially increased among patients with lip, oral cavity/pharyngeal, colon and rectal, pancreatic and lung cancers when compared with cancer-free subjects; whereas among women, the relative risk was substantially increased among patients with colon and rectal cancers. Conclusion Our study observed an increased risk of suicide among patients with cancer that varied according to the anatomical cancer site, even after accounting for clinical comorbidities and psychiatric illness. Our findings indicate a need for social support and suicide prevention strategies for patients with cancer.