Association between poor oral health and gastric cancer: A prospective cohort study.

Poor oral health may be involved in the pathogenesis of gastric cancer, however, some aspects have not been explored. Further, for previously studied aspects, for example, tooth-loss, the findings are inconsistent. We conducted a prospective cohort study of 19,831 participants from Uppsala, Sweden, cancer-free at baseline in 1973-1974 and followed until 2012 through linkage to national registers. We found that individuals with fewest teeth at baseline had an increased risk of gastric cancer relative to subjects with all examined teeth present (p = 1.75e-2). Presence of denture-associated lesions was also associated with an increased risk of gastric cancer (p = 1.00e-4). However, these excess risks significantly varied with attained age; estimated hazard ratio (HR) at attained age 50 for tooth loss was 4.24 [95% confidence interval (CI) 1.83-9.80] and 5.91 (95% CI 2.76-12.63) for denture-associated lesions, decreasing at an estimated 4% and 6% per year respectively, resulting in HR of 1.54 (95% CI 0.90-2.64) for tooth loss and HR 1.29 (95% CI 0.90-1.85) for denture-associated lesions at attained age 75. No increased risk of gastric cancer was found for individuals with higher levels of dental plaque, or with Candida-related or tongue lesions. In conclusion, tooth-loss and denture-associated lesions are associated with increased risks of gastric cancer. Previous conflicting findings of tooth-loss and gastric cancer risk may partly be explained by the age-varying relative risk of gastric cancer.