Poor oral hygiene behavior is associated with an increased risk of gastric cancer: A population‐based case‐control study in China

Abstract Background Poor oral health may be a significant risk factor for gastric cancer (GC); however, previous results are not consistent. Here, we investigated the effect of oral health on GC and effect modification by other factors. Methods We conducted a population‐based case‐control study in Taixing, China. Participants aged between 40 and 85 years and who had lived in Taixing for at least 5 years were included. The GC cases were confirmed by endoscopy and pathological diagnosis, and the controls were randomly selected using the frequency‐matching method. Unconditional logistic regression models were used to derive odds ratios (ORs) and 95% confidence intervals (CIs) of oral health for GC risk after adjusting for confounders and risk factors. Results Overall, 901 GC cases and 1972 controls were included. Tooth loss was not significantly associated with an increased risk of GC (yes vs . no, OR = 1.08, 95% CI 0.88 to 1.33). Compared with toothbrushing at least twice per day, toothbrushing once per day or less was associated with an increased risk of GC (OR = 2.39, 95% CI 1.94 to 2.94), and was more pronounced in esophagogastric junction cancer and intestinal‐type GC. There was no significant interaction between the indicators of oral health and age, sex, tobacco smoking, alcohol drinking, and Helicobacter pylori seropositivity. Conclusion Poor oral hygiene behavior is associated with an increased risk of GC, and this positive association is consistent across all GC subgroups classified by anatomy and histology. Further studies are needed to explore the possible mechanisms behind this association.