Mental illness and non-metastatic colorectal cancer treatment and survival, a nationwide study of almost 70,000 patients.

Background and purpose: The impact of mental illness on treatment and outcomes for patients with colorectal cancer (CRC) has not been investigated with potential confounders and mediators accounted for.

Patients and methods: Colorectal Cancer Database (CRCBaSe), a linked national registry database, was used to analyse stage I-III CRC patients diagnosed in Sweden between 2008 and 2021. The exposure of interest was a history of mental illness. Treatment outcomes were analysed with logistic regressions. Flexible parametric models were fitted for survival analysis. Analyses were adjusted for pre-specified confounders.

Results: Patients with a history of severe mental illness presented with more advanced tumours and comorbidities. They were more likely to undergo emergency surgery (OR 1.56, 95% CI 1.32-1.84) and less likely to receive adjuvant treatment (OR 0.65, 95% CI 0.53-0.80) than patients with no history of mental illness. Five-year standardised overall survival (OS) was worse for those with a history of mild and severe mental illness, 64.6% (95%CI 63.9-65.3) and 61.8% (95%CI 59.7-63.8) compared to those without 69.3% (95%CI 68.9-69.7). Although time to recurrence was not significantly impacted, standardised survival after recurrence was worse for patients with a history of severe mental illness, with a 3-year survival after recurrence of 24% compared to 30% in those without a history of mental illness.

Interpretation: Although the differences were smaller compared to previous studies, patients with a history of mental illnesses still do worse. The management of CRC patients with psychiatric comorbidities presents complex challenges necessitating personalised solutions.