The association between poor dental health and gastric cancer risk: a nationwide cohort and sibling-controlled study

Abstract

Background: Poor dental health has been linked to an increased risk of gastric cancer (GC), but previous studies were limited by their retrospective design and relatively small sample size.

Methods: We followed a nationwide cohort of 5,888,034 Swedish adults over the age of 19 who visited a dentist between 2009 and 2016. Additionally, a nested case-control study was conducted by comparing incident GC cases to their siblings. Cox regression analyses, using attained age as the timescale and adjusting for potential confounders, were performed to evaluate the association between various dental health conditions and the risk of GC. In addition, we stratified our analyses by sex and age and conducted various sensitivity analyses to ensure the robustness of our findings.

Results: Over an average follow-up of 6.4 years, we identified 3993 new GC cases, including 1241 cardia GC and 2752 non-cardia GC. Compared to individuals with healthy teeth, those with periodontitis had an 11% and 25% increased risk of GC and cardia GC, respectively. The positive associations between odontogenic inflammation and the risk of GC were consistent in sibling-controlled analyses. We also observed a dose-response relationship between the number of remaining teeth and the risk of GC, with fewer teeth associated with higher risks. Additionally, we did not find significant interactions between dental inflammatory conditions and the number of remaining teeth in relation to the risk of GC or its subtypes. Our findings were consistent across different sex and age subgroups and in sensitivity analyses.

Conclusions: This study provides the largest prospective cohort study evidence to date, along with the first sibling-controlled comparisons, supporting the association between poor dental health and GC risk. Promoting dental health in the general population could have significant public health implications in preventing this disease.

Keywords: Cohort study; Dental health; Gastric cancer; Population-based; Register-based; Sibling-controlled.

Fig. 1

Flowchart of the cohort assembly process. Abbreviations: CR, the Swedish Cancer Register; GC, gastric cancer; TPR, the Swedish Total Population Register; NPR, the Swedish National Patient Register; LISA, the longitudinal integrated database for health insurance and labour market studies; DHR, the Swedish Dental Health Register; MGR, the Swedish Multi-Generation Register

Fig. 2

The association between baseline dental health condition and the risk of gastric cancer in the cohort analysis. All HR and 95% CI estimates were derived from Cox models with attained age as timescale: minimally adjusted models were adjusted for sex and age at entry; fully adjusted models were adjusted for sex, age at entry, family income, education, family history of gastric cancer, smoking-related diseases, and alcohol-related diseases. Trend analyses were performed by Cochran-Armitage test. The “unknown” group was excluded from the calculation of p-trend. Abbreviations: IR, incidence rate; HR, hazard ratio; CI, confidence interval. *: p < 0.05; **: p < 0.01; ***: p < 0.001

Fig. 3

The association between baseline dental health condition and the risk of cardia and non-cardia gastric cancer in the cohort analysis. All HR and 95% CI estimates were derived from Cox models with attained age as timescale, adjusted for sex, age at entry, family income, education, family history of gastric cancer, smoking-related diseases, and alcohol-related diseases. Trend analyses were performed by Cochran-Armitage test. The “unknown” group was excluded from the calculation of p-trend. Abbreviations: IR, incidence rate; HR, hazard ratio; CI, confidence interval. *: p < 0.05; **: p < 0.01; ***: p < 0.001

Fig. 4

Exposure-response curve for the association of remaining tooth number at baseline with the risk of gastric cancer and its anatomical subtypes among individuals in the Swedish Dental Health Register, 2009–2016. A Total gastric cancer; B cardia gastric cancer; C non-cardia gastric cancer. The dark blue solid line represents the point estimates and the black dash lines indicate corresponding 95% CIs, which were derived from Cox models with attained age as timescale, adjusted for sex, age at entry, family income, education, family history of gastric cancer, smoking-related diseases, and alcohol-related diseases