Periodontitis and breast cancer risk: A systematic review with meta-epidemiological analysis.
TL;DR
A modest association between periodontitis and increased breast cancer risk is confirmed, but the strength of this association appears to be inflated by methodological limitations in the primary studies, particularly in case-control designs and in studies with limited adjustment for confounding factors.
Abstract
Background
The association between periodontitis and breast cancer (BC) risk has been reported, but with considerable variability in effect estimates across studies. This meta-epidemiological study aimed to systematically evaluate how methodological characteristics of primary studies influence these reported effect estimates.
Methods
Cohort and case-control studies were searched in electronic databases up to February 2025. Study quality was assessed using the Newcastle-Ottawa Scale. Meta-analyses were conducted to estimate risk measures (relative risk [RR] and 95% confidence intervals [CI]). Meta-regression and subgroup analyses were performed to investigate potential variability in effect estimates.
Results
Among the 19 included studies, although the overall pooled estimate indicated a 19% higher risk of BC in women with periodontitis compared with those without periodontitis (RR = 1.19; 95%CI, 1.05-1.34), meta-epidemiological analyses showed attenuated estimates in prospective vs. case-control studies (RR = 1.05 vs. 1.54), high- vs. moderate-quality studies (RR = 1.09 vs. 2.10), and adjusted vs. unadjusted analyses (RR = 1.07 vs. 1.48) (p < 0.05).
Conclusion
Although a small association between periodontitis and BC risk was observed, its magnitude appears to be overestimated in lower-quality, case-control, and inadequately adjusted studies. These findings underscore the importance of methodological rigor in the interpretation of the evidence. PLAIN LANGUAGE SUMMARY This meta-epidemiological study, based on a systematic and rigorous literature search, confirmed a modest association between periodontitis and increased breast cancer risk. The strength of this association appears to be inflated by methodological limitations in the primary studies, particularly in case-control designs and in studies with limited adjustment for confounding factors. These findings emphasize the need for high-quality prospective studies to more accurately characterize this relationship.