Patterns of presentation, diagnosis, and treatment in older patients with colon cancer and comorbid dementia.

OBJECTIVES: To estimate patterns of colon cancer presentation, diagnosis, and treatment according to history of dementia using National Cancer Institute (NCI) Surveillance, Epidemiology, and End-Result (SEER) Medicare data.

DESIGN: Population-level cohort study.

SETTING: NCI's SEER-Medicare database.

PARTICIPANTS: A total of 17,507 individuals aged 67 and older with invasive colon cancer (Stage I-IV) were identified from the 1993-1996 SEER file. Medicare files were evaluated to determine which patients had an antecedent diagnosis of dementia.

MEASUREMENTS: Parameters relating to the cohort's patterns of presentation and care were estimated using logistic regressions.

RESULTS: The prevalence of dementia in the cohort of newly diagnosed colon cancer patients was 6.8% (1,184/17,507). Adjusting for possible confounders, dementia patients were twice as likely to have colon cancer reported after death (i.e., autopsy or death certificate) (adjusted odds ratio (AOR)=2.31, 95% confidence interval (CI)=1.79-3.00). Of those diagnosed before death (n=17,049), dementia patients were twice as likely to be diagnosed noninvasively than with tissue evaluation (i.e., positive histology) (AOR=2.02 95% CI=1.63-2.51). Of patients with Stage I -III disease (n=12,728), patients with dementia were half as likely to receive surgical resection (AOR=0.48, 95% CI=0.33-0.70). Furthermore, of those with resected Stage III colon cancer (n=3,386), dementia patients were 78% less likely to receive adjuvant 5-fluorouracil (AOR=0.22, 95% CI=0.13-0.36).

CONCLUSION: Although the incidences of dementia and cancer rise with age, little is known about the effect of dementia on cancer presentation and treatment. Elderly colon cancer patients are less likely to receive invasive diagnostic methods or curative-intent therapies. The utility of anticancer therapies in patients with dementia merits further study.