Prevalence of Depression and Cancer - A systematic review.

Objective: While comorbidity of different forms of cancer and clinical depression is reported for many single studies, representative and global overviews are scarce. Methods: A systematic review was carried out (mainly based on Medline, Embase, Cochrane, PsychLit, and Psyndex) to identify studies in adult cancer patients from 2007 to 2019. Studies with noncancer populations and cancer survivors were excluded. Assessment methods of depression were chart-based diagnoses, interview-based and self-report questionnaires. Quality and plausibility were checked using the adapted Downs & Black checklist. Results: For all 210 included studies the prevalence rate of clinical depression varied from 7.9 % to 32.4 %, with a mean of 21.2 % depression for different (mixed) cancer entities. The different methods of assessment have led to under- (especially charts-based diagnoses) as well as overreporting for some forms of cancer. In general, the different assessment forms show an acceptable variation in prevalence. Conclusions: The risk for a cancer patient to suffer a clinical depression during the first year after diagnoses is 15 % to 20 %, meaning every fifth or sixth patients. Different cancer entities, stage of cancer and treatments as well as different cultural and medical backgrounds show only slight variation in prevalence rates.