Mental health conditions and incident cancer: a prospective cohort study of 402,255 UK Biobank participants

1 Abstract Background Mental health conditions (MHCs) affect both psychological health and biological systems and have been linked to cancer risk. However, evidence from epidemiological studies remains inconsistent. Aim The study aims to investigate the associations of five MHCs (depressive disorders (DD), anxiety disorders (AD), bipolar disorder (BD), schizophrenia (SZ), and post-traumatic stress disorder (PTSD)) with overall and site-specific cancer risk. Dose-response relationship by depressive symptom severity and effect modifications by sex were also explored. Methods A population-based prospective cohort study was conducted on 402,255 UK Biobank participants, who were free from cancer, with a median follow-up of 13.4 years. Cox proportional hazard models were used to examine the associations of the five MHCs, and self-reported depressive symptom severity with overall and site-specific incident cancers, adjusting for sociodemographic, lifestyle and health-related confounders. Results Over a median follow-up of 13.4 years, 68,065 (17%) incident cancer cases were recorded. DD (HR 1.18; 95% CI 1.13-1.23), AD (HR: 1.17, 95%CI: 1.11-1.24), and BD (HR: 1.29, 95%CI: 1.11-1.51) were associated with increased overall cancer risk. No significant association was found for SZ and PTSD. The associations of DD (HR: 1.27, 95%CI: 1.18-1.35) and BD (HR: 1.54, 95%CI: 1.26-1.88) were only significant in men. AD and DD were positively associated with lung, blood, and liver cancers, while AD was also associated with prostate cancer. A dose-response relationship was observed between depressive symptom severity and cancer risk. Conclusion MHCs were associated with a higher risk of overall and some site-specific cancers. While causality cannot be assumed, diagnoses of MHCs could be useful for cancer risk stratification and prevention.