Risk of cancer among patients with depressive disorder: a meta-analysis and implications

Objective: The question of cancer risk in individuals with depression is unclear, primarily because of the heterogeneity of the assessment of depression in the published literature. To clarify the mixed findings, this analysis was limited to articles that used a reliable method of ascertaining depressive disorder. Methods: We searched PubMed, EMBASE, and the Cochrane Library to identify studies investigating the effect of depression on subsequent risk of cancer, defining depression based on the criteria in the Diagnostic and Statistical Manual of Mental Disorders (DSM) and/or the International Classification of Disease (ICD). We calculated a pooled odds ratio (OR) for developing cancer with the 95% confidence interval (CI). Results: Nine studies fulfilled the eligibility criteria. In a random-effects model, patients with depressive disorder were at increased risk for cancer (OR, 1.26; 95% CI, 1.06–1.50, P = 0.01). However, a significant effect was observed only in low-quality studies (OR, 1.31; 95% CI, 1.05–1.63, P = 0.018), and not in high-quality studies (OR, 1.15; 95% CI, 0.85–1.56, P = 0.366). Conclusion: Our results did not demonstrate that people with depressive disorder are at increased risk for developing cancer. Well-designed prospective studies of recurrent or persistent depressive disorder that control for lifestyle factors including smoking are warranted.