Suicide after colorectal cancer-a national population-based study

A cancer diagnosis is often associated with physical as well as emotional distress. Previous studies indicate a higher risk for suicide in patients diagnosed with cancer. The aim of this study was to investigate the prevalence of death by suicide in a national cohort of patients with newly diagnosed colorectal cancer compared with a matched control group to determine if patients with colorectal cancer had an increased incidence of death by suicide.

This national Swedish cohort was retrieved from the register-based research database CRCBaSe, which includes all patients diagnosed with colorectal cancer between 1997-2006 (rectal) and 2008-2016 (colon) and six controls for each patient matched by age, sex, and county. Cause specific mortality due to suicide was modelled using Cox proportional hazards model and adjusted for known risk factors.

The main analysis included patients operated for colorectal cancer, 55 578 patients compared with 307 888 controls. The first year after diagnosis the hazard ratio (HR) for suicide among patients operated for colorectal cancer was 1.86 (CI: 1.18-2.95) compared to controls. Suicide was more common among men than women (HR 2.08; 1.26-3.42 vs. 1.09; 0.32-3.75). A subgroup analysis of the 9198 patients who did not undergo surgery after diagnoses found a seven-fold increase of suicide (HR 7.03; 3.10-15.91).

Suicide after surgery for colorectal cancer was almost twice as high as in the control group, mainly driven by excess mortality among men. Although the cases were few in the subgroup of nonoperated patients, the considerably higher risk of suicide indicates that more resources might be needed in this group. Evaluation of risk factors for suicide among patients with colorectal cancer should be performed for early identification of individuals at risk.