Previous studies reposted controversial results in the association between depression and risk of cancer. The purpose of this study is to investigate mental disorders and risk of cancer in a population-cased case–control study.Methods
We used insurance claims data from the National Health Insurance Research Database, a universal insurance program with a coverage rate of more than 99% of the population in Taiwan. We identified 41 180 patients with newly diagnosed cancer and randomly selected 164 720 non-cancer controls which matched with age and sex (case-control ratio = 4:1) in 2005–2008. This study used multivariate logistic regression analysis to calculated odds ratios (ORs) and 95% confidence intervals (CIs) of mental disorders associated with cancer risk adjusted for sociodemographic factors and co-existing diseases.Results
The prevalence of mental disorders for cancer patients and controls were 18.7% and 24.8%, respectively. People with mental disorders had higher risk of cancer compared with people without mental disorders (OR = 1.38, 95% CI = 1.34–1.41). Liver cirrhosis was associated with cancer risk (OR = 2.80, 95% CI = 2.59-3.03). Experienced emergency care or inpatient care for mental disorders were significant factors associated with cancer risk. The increased risk of cancer was associated with higher number of outpatient visits for psychiatric care.Conclusions
Mental disorders could be considered as a risk factor for cancer. The severity independent effect exists in the association between mental disorders and cancer risk.