Women who have periodontal disease are at greater risk for breast cancer, especially if they smoke or recently quit smoking, according to a new study published in Cancer Epidemiology, Biomarkers, and Prevention.

Researchers looked at data from a prospective cohort of 73,737 postmenopausal women enrolled in the Women’s Health Initiative Observational Study. A total of 26.1% of the women had periodontal disease. After a median follow-up of 6.7 years, 2,124 women developed breast cancer; the risk was 14% higher for women who had periodontal disease. 

Because periodontal disease can be more severe in women who have a history of smoking, the researchers also compared data based on the women’s smoking status. Women with periodontal disease who had quit smoking within the past 20 years had a 36% higher risk of developing breast cancer, those who were currently smoking had a 32% higher risk, those who had quit smoking more than 20 years ago had an 8% increased risk, and those who had never smoked had a 6% increased risk.

Although the study was large and well designed, the researchers caution that further studies are needed to explore the mechanism and effects of periodontal intervention to fully understand the relationship between the gum disease and breast cancer risk.