The impact of severe mental illness on lung cancer mortality of lung cancer patients in Finland in 1990-2013: a register-based cohort study

Background While the link between severe mental illness (SMI) and elevated cancer mortality is well established, few studies have examined lung cancer survival and SMI in detail. Our study compared cancer-specific mortality in lung cancer patients with and without a history of SMI, and whether mortality differences could be explained by cancer stage at presentation, comorbidity or differences in cancer treatment. Methods We identified patients with their first lung cancer diagnosis in 1990-2013 from the Finnish Cancer Registry, their preceding hospital admissions due to SMI from the Hospital Discharge Register and deaths from the Causes of Death statistics. Competing risk analyses were used to estimate hazard ratios (HR) for the impact of SMI on mortality. Results Out of the 37,852 lung cancer cases, 12% had a history of SMI. Cancer-specific mortality differences were found between patient groups in some cancer types after controlling for stage at representation and treatment. Men with history of psychosis had excess mortality risk (HR 1.24, 1.06-1.45) in squamous cell carcinoma. Similar excess risk was found among women with psychosis in small-cell carcinoma (HR=1.76, 1.41-2.19) and in squamous cell carcinoma (HR=1.67, 1.26-2.20) and among women with mood disorders in adenocarcinoma (HR=1.37, 1.08-1.74). Patient group differences in HRs in five-year mortality did not markedly change from the 1990s. Conclusions We found elevated cancer-specific mortality among persons with a history of SMI. Collaboration between patients, mental health care professionals, and oncological teams is needed to reduce the mortality gap between cancer patients with and without SMI. Abstract: 248 words (Eur J Cancer: 250 + list of keywords) Manuscript: 2558 words (Eur J Cancer: 2500) 248 words (Eur J Cancer: 250 + list of keywords) Manuscript: 2558 words (Eur J Cancer: 2500)