Cancer and schizophrenia

On the basis of articles published in 2018, 2019 and 2020, the first aim of this review is to present estimates of incidence rates and excess mortality of overall cancer and organ-specific cancers for patients with schizophrenia compared with the general population.The second aim is to explore if underdiagnosis and undertreatment can explain - at least partly - the increased mortality of cancer in patients with schizophrenia compared with the general population.

Patients diagnosed with schizophrenia have an approximately 50% increased risk of death by cancer compared to age and sex-matched people in the general population. Studies have confirmed an increased mortality from breast, lung and colon cancer in patients with schizophrenia.Analyses of incidence of cancer revealed contradicting results, with some studies showing no increase in incidence and others a modestly increased incidence in overall cancer. Studies of incidence of specific types of cancers showed modestly increased risk of pancreas, oesophagus, breast cancer and contradicting results regarding lung cancer.In studies identified that compared to the general population, patients with schizophrenia were at an increased risk of not being diagnosed or treated for cancer before death of cancer. In addition, patients with schizophrenia had lower chances of getting optimal treatment for colon cancer after diagnosis.

This review indicates that patients with schizophrenia are at increased risk of dying of cancer and of several specific types of cancer. This increased mortality can be reduced if the price of tobacco is increased, if smoking cessation programmes are offered systematically, screening programs better implemented in this highly vulnerable group, and if procedures to facilitate access to early diagnosis and effective treatment are implemented.