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.