Cancer risk in individuals with psychiatric disorders: population-based cohort study

The risk of cancers associated with psychiatric disorders is understudied.

To investigate whether cancer risk varies with the presence of psychiatric disorders.

Patients diagnosed with psychiatric disorders in South Korea between 1 January and 31 December 2017 were included in the study and referred to as the psychiatric disorder group. The non-psychiatric-disorder group, selected using a stratified random sampling technique based on age and gender, comprised individuals who had never been diagnosed with a psychiatric disorder. The primary outcome was a new cancer diagnosis, assessed over a 5-year period (1 January 2018 to 31 December 2022).

Following 1:1 propensity score matching, the final analysis included data for 686 570 adults (343 285 in each group). The cancer incidence in the psychiatric disorder group from 2018 to 2022 was 15.4% (52 948/343 285), whereas in the non-psychiatric-disorder group, it was 12.8% (43 989/343 285). Cox regression analysis revealed that the psychiatric disorder group had a 23% higher occurrence of cancer compared with non-psychiatric-disorder controls (hazard ratio: 1.23, 95% CI: 1.21, 1.24; P < 0.001). Significant associations between cancer incidence and specific psychiatric disorders were observed in individuals with alcohol-related disorders (hazard ratio: 1.27, 95% CI: 1.23, 1.32; P < 0.001), anxiety disorders (hazard ratio: 1.15, 95% CI: 1.14, 1.17; P < 0.001) and major depressive disorder (hazard ratio: 1.16, 95% CI: 1.15, 1.18; P < 0.001).

Individuals with psychiatric disorders were more likely to develop cancer than those without. We identified associations of alcohol-related disorders, anxiety disorders and major depressive disorder with cancer risk.