Effect of mental disorders on diagnosis, treatment, and survival of older adults with colon cancer

OBJECTIVES: To evaluate the extent to which preexisting mental disorders influence diagnosis, treatment, and survival in older adults with colon cancer. DESIGN: Retrospective cohort study. SETTING: The Surveillance, Epidemiology and End Results (SEER)–Medicare linked database. PARTICIPANTS: Eighty thousand six hundred seventy participants, aged 67 and older with a diagnosis of colon cancer. MEASUREMENTS: The association between the presence of a preexisting mental disorder and the stage of colon cancer at diagnosis, receipt of cancer treatment, and overall and colon cancer‐specific mortality were assessed using Cox proportional hazards regression and logistic regression. RESULTS: Participants with mental disorders were more likely to have been diagnosed with colon cancer at autopsy (4.4% vs 1.1%; P<.001) and at an unknown stage of cancer (14.6% vs 6.2%; P<.001); to have received no surgery, chemotherapy, or radiation therapy (adjusted risk ratio (ARR)=2.09, 95% confidence interval (CI)=1.86–2.35); and to have received no chemotherapy for Stage 3 cancer (ARR=1.63, 95% CI=1.49–1.79). The rate of overall mortality (hazard ratio (HR)=1.33, 95% CI=1.31–1.36) and colon cancer‐specific mortality (HR=1.23, 95% CI=1.19–1.27) was substantially higher in participants with a preexisting mental disorder than in their counterparts. All of these associations were particularly pronounced in participants with psychotic disorders and those with dementia. CONCLUSION: Public health initiatives are needed to improve colon cancer detection and treatment in older adults with mental disorders.