Postmenopausal women with periodontal disease are more likely to develop breast cancer than those with healthy gums, according to the American Association for Cancer Research.
A study by the University of Buffalo School of Public Health and Health Professions monitored 73,737 postmenopausal women enrolled in the Women’s Health Initiative Observational Study who did not have any previous breast cancer and found periodontal disease in 26.1% of them.
After a mean follow-up time of 6.7 years, 2,124 of these women were diagnosed with breast cancer. Among all of the women, the risk of breast cancer was 14% higher in those with periodontal disease.
Women with periodontal disease who had quit smoking within the past 20 years had a 36% higher risk of breast cancer, while women overall who were smoking at the time of the study had a 32% higher risk.
Those who had never smoked or who had quit more than 20 years ago had a 6% and 8% increased risk, respectively, if they had periodontal disease. The researchers said that previous exposure to smoking might affect the carcinogenic process since the highest risk was found in smokers who had quit within the past 20 years.
“We know that the bacteria in the mouths of current and former smokers who quit recently are different from those in the mouths of nonsmokers,” said Jo L. Freudenheim, PhD, of the University of Buffalo and lead author of the study.
The researchers noted several explanations for the link between periodontal disease and breast cancer. First, there may be systemic inflammation with periodontal disease that affects the breast tissues. Or, bacteria from the mouth can enter the circulatory system and affect the tissue. Further studies are needed to establish a causal link, though.
“If we can study periodontal disease and breast cancer in other populations, and if we can do more detailed study of the characteristics of the periodontal disease, it would help us understand if there is a relationship,” said Freudenheim. “There is still much to understand about the role, if any, of oral bacteria and breast cancer.”
The women in the study self-reported their periodontal disease status after being asked if a dentist had ever told them that they had it. Also, the subjects already were enrolled in a health study, so they were more likely than the general population to be conscious of health issues. The general population, then, would have higher rates of periodontal disease and other risk factors like smoking, diabetes, and obesity.
The study was published by Cancer Epidemiology, Biomarkers & Prevention. It was funded by the National Heart, Lung, and Blood Institute; the National Institutes of Health; and the US Department of Health and Human Services.