Association between chemotherapy and cognitive impairments in a large cohort of patients with colorectal cancer.

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Abstract

No population-based study has been conducted on the relationship between chemotherapy and the risk of cognitive impairments in patients with colorectal cancer. This study aimed to determine this association in a large population-based cohort of patients. We studied 72,374 men and women who were diagnosed with stages I-III colorectal cancer at age ≥ 65 years from 1991 through 2002 from 16 regions in the Surveillance, Epidemiology and End Results program who were free of cognitive impairments at baseline with up to 17 years of follow-up and also studied 15,921 matched cohorts based on the propensity of receiving chemotherapy. The cumulative incidence of drug-induced dementia at 5 years was 16.2 cases per 1,000 persons for the chemotherapy group and 12.4 cases per 1,000 persons for the no chemotherapy group. Overall, patients who received chemotherapy were 24% significantly more likely to develop drug-induced dementia compared to those without chemotherapy after adjusting for patient and tumor characteristics (hazard ratio 1.24, 95% confidence interval 1.05-1.47). The significantly increased risk was only observed in those without mood disorder who received chemotherapy in the entire cohort (1.26, 1.06-1.50) and in the matched cohort (1.29, 1.04-1.59). The risk of developing Alzheimer's disease, vascular dementia or other dementias was significantly lower in patients receiving chemotherapy compared to those without chemotherapy regardless of mood disorder status. In conclusion, there was a significant association between chemotherapy and the risk of developing drug-induced dementia in patients with colorectal cancer without mood disorder, but chemotherapy was associated with a decreased risk of other dementias.