Effect Modification by Age and Comorbidities on the Association Between Periodontitis and Female Breast Cancer: A Population-based Case-control Study

Abstract Background: The association between periodontitis and female breast cancer is not clear. The purpose of this study is to assess that periodontitis was associated with the risk of female breast cancer.Methods: Using claims data taken from the 1997–2013 Taiwanese National Health Insurance Research Database (NHIRD), we identified 60,756 newly-diagnosed female breast cancer patients during the period 2003–2013 from all beneficiaries. We then randomly selected 243,024 women without breast cancer matching (1:4) for age and the year of the index date during 1997–2013 from a one million representative population acting as the control group. A conditional logistic regression analysis was used to examine the association between periodontitis and the risk of breast cancer, shown as an odds ratio (OR) with a 95% confidence interval (CI) after adjustments for the Charlson Comorbidity Index (CCI), geographic region and level of urbanization.Results: The mean ± standard deviation age was 53 ± 14 years. After adjusting for potential confounders, the risk of female breast cancer was found to be associated with a history of periodontitis (OR, 1.12; 95% CI, 1.10-1.14). Such an association was significantly different between patients aged < 65 years (OR, 1.09; 95% CI, 1.06–1.11) and patients aged ≥ 65 years (OR, 1.23; 95% CI, 1.18–1.28; p for interaction 0 (OR, 0.99; 95% CI, 0.96–1.03; p for interaction <0.001). The highest level of urbanization was also associated with the risk of breast cancer.Conclusions: This nationwide, population-based case-control study demonstrated that periodontitis was significantly associated with the risk of female breast cancer and such an association was modified by both age and comorbidities.