Association of pre-existing depression with all-cause, cancer-related, and noncancer-related mortality among 5-year cancer survivors: a population-based cohort study

Previous studies on the association between mental health and mortality in patients with cancer have reported contradictory results. We conducted a population-based cohort study to determine whether pre-existing depression is associated with all-cause and cause-specific mortality after cancer diagnosis. We included 5-year cancer survivors, identified from the National Health Insurance Scheme Health Screening Cohort between January 1, 2004 and December 31, 2009. Cox proportional hazards models were used to calculate hazard ratios and 95% confidence intervals (CI) to assess the association between pre-existing depression and all-cause, cancer-related, and noncancer-related mortality among 5-year cancer survivors. After adjustment for sociodemographics, lifestyle, and clinical status, the multivariable adjusted hazard ratios (95% CIs) for all-cause, cancer-related, and noncancer-related mortality among 5-year cancer survivors with pre-existing depression were 1.52 (1.13–2.05), 1.17 (0.75–1.81), and 2.07 (1.38–3.10) compared with those without pre-existing depression, respectively. Significant associations between pre-existing depression and mortalities (all-cause and noncancer-related mortality) were only observed among male cancer survivors. Our findings suggest that depression is associated with all-cause mortality after cancer diagnosis and that greater efforts should be focused on the long-term survival of patients with cancer with pre-existing depression, especially in male cancer survivors.