Risk of Dementia in Gastric Cancer Survivors Who Underwent Gastrectomy: A Nationwide Study in Korea

Purpose: This study was designed to compare the risk of dementia, including Alzheimer’s disease (AD) and vascular dementia (VaD), between gastric cancer patients who underwent gastrectomy and the general population. Methods: All patients (n = 63,998) aged ≥ 50 years who received a diagnosis of gastric cancer and underwent curative gastrectomy between 2007 and 2012 and a noncancer control population (n = 203,276), matched by age and sex, were identified from the Korean National Health Insurance Services and traced until 2017. Hazard ratios and 95% confidence intervals for dementia were calculated with a Cox regression analysis. Results: Gastric cancer patients who received a gastrectomy showed an increased risk of AD [adjusted hazard ration (aHR) 1.08, 95% confidence interval (CI) 1.03–1.14], and the risk was especially marked for those who received a total gastrectomy (aHR 1.39, 95% CI 1.25–1.54). Gastric cancer survivors showed a decreased risk for VaD (aHR 0.85; 95% CI 0.73–0.98) regardless of operation type. Those who received continual vitamin B₁₂ supplementation after a total gastrectomy were less likely than controls to develop AD (aHR 0.71; 95% CI 0.54–0.92). Conclusions: Compared with controls, gastric cancer patients who received a total gastrectomy had an increased incidence of AD and a decreased risk of VaD. Our results suggest that vitamin B₁₂ deficiency might play a role in the development of AD and highlight the need for vitamin B₁₂ supplementation after total gastrectomy.