Prevalence of mental disorders in patients with cancer compared to matched controls - secondary analysis of two nationally representative surveys.

Aim: To compare prevalence rates of mental disorders in patients with cancer and general population controls.

Method: In two stratified nationally representative surveys, the 12-month prevalence of mental disorders was assessed in 2141 patients with cancer and 4883 general population controls by the standardized Composite International Diagnostic Interview (CIDI). We determined odds ratios (ORs) to compare the odds for mental disorders (combined and subtypes) in cancer patients with age- and gender-matched controls.

Results: The 12-month prevalences rate for any mental disorder was significantly higher in patients with cancer compared to controls (OR 1.28, 95% CI 1.14-1.45). Prevalence rates were at least two times higher for unipolar mood disorders (major depression: OR 2.07, 95% CI 1.71-2.51; dysthymia: OR 2.93, 95% CI 2.13-4.02) and mental disorders due to a general medical condition (OR 3.31, 95% CI 2.32-4.71). There was no significant elevation for anxiety disorders overall (OR 0.95, 95% CI 0.81-1.11). Mildly elevated prevalence rates emerged for post-traumatic stress disorder (OR 1.57, 95% CI 1.11-2.23) and social phobia (OR 1.57, 95% CI 1.07-2.31), while specific phobia (OR 0.82, 95% CI 0.67-1.00) and agoraphobia (OR 0.49, 95% CI 0.33-0.73) were significantly less frequent in cancer.

Conclusions: While elevated depression rates reinforce the need for its systematic diagnosis and treatment, lower prevalences were unexpected given previous evidence. Whether realistic illness-related fears and worries contribute to lower occurrence of anxiety disorders with excessive fears in cancer may be of interest to future research.