Risk of dementia in colorectal cancer patients receiving chemotherapy: A nationwide cohort study

Background: Studies have reported conflicting evidence regarding whether chemotherapy leads to dementia. This study aimed to determine whether chemotherapy increases dementia risk in Taiwanese patients with colorectal cancer (CRC). Methods: Data from the Taiwan Cancer Registry and National Health Insurance Research Database were used. Patients newly diagnosed as having CRC between 2007 and 2015 without prior history of dementia or neurodegenerative disorders were identified. Based on whether they underwent chemotherapy, patients were divided into chemotherapy and non-chemotherapy groups. Those who later developed dementia were identified using validated diagnostic codes. The Fine and Gray subdistribution hazard model for all-cause dementia with competing risk of death was applied for all patients or each stratified group. Results: A total of 76,130 patients with CRC were included, with 45,872 (60.25%) in the chemotherapy group and 30,258 (39.75%) in the non-chemotherapy group. A higher incidence of dementia was observed in the non-chemotherapy group compared with the chemotherapy group (3.75% vs. 2.40%, p < 0.0001), but the risk of dementia did not differ between the groups (adjusted subdistribution hazard ratio [HRSD] = 0.97, 95% confidence interval [CI]: 0.88-1.06, p = 0.492). In the stratified analysis, chemotherapy was a risk factor for dementia in patients aged > 80 years (adjusted HRSD = 1.20, 95% CI: 1.03-1.40, p = 0.0190), whereas gender, clinical cancer stage, comorbidities, surgery, and radiation therapy had no impact on the risk of dementia. Conclusion: Chemotherapy increased the risk of dementia in elderly patients with CRC, highlighting the necessity to monitor their cognitive function after chemotherapy.