Objective: To investigate the association between mental illness and cancer incidence, mortality and case fatality.
Method: A population-based record linkage study was undertaken based on 172 932 patients of mental health services in Western Australia. Records of mental health service contacts were linked with cancer registrations and death records.
Results: While there was little difference in overall cancer incidence rates between psychiatric patients and the general community (RR in males 1.05, 95% CI 1.02–1.09, RR in females 1.02, 0.98–1.05), cancer mortality was 39% higher in males (95% CI: 32–46%) and 24% higher in females (17–32%).
Conclusion: People with mental illness in Western Australia do not show an increased incidence rate of cancer, but do have higher cancer mortality. This was attributed to a higher cancer case fatality rate among people with mental illness.