Gum disease, or periodontal disease, is a chronic inflammatory condition of the gums that affects half of Americans over 30. Gingivitis, the mildest form of periodontal disease, is marked by swollen and bleeding gums. If not addressed gingivitis can advance to more severe stages of periodontal disease, which threaten the tissues and bones that support teeth. In advanced periodontal disease, gums recede away from the teeth, creating “pockets” that become infected. Eventually, teeth loosening or loss results. Research has already shown this common, but serious periodontal disease has also been linked to cardiovascular disease, diabetes, and Alzheimer’s disease, and many other chronic health issues. A study published in Cancer Epidemiology, Biomarkers & Prevention on December 21, 2015 now indicates that periodontal disease may be connected to an increased risk of getting breast cancer in postmenopausal women, especially in those with a history of smoking.
A team of researchers at the University of Buffalo led by Jo L. Freudenheim, PhD, used previously collected data on the health of 73,737 postmenopausal women from a study called the Women’s Health Initiative. The researchers selected data from women who had no history of breast cancer at the beginning of the study. Of those women, about one in four reported a previous diagnosis of periodontal disease, but that number was higher, at more than one in three, in people who smoked or used to smoke. The researchers then watched the data as it moved forward in time to see if any of the women developed breast cancer and whether periodontal disease might be related. After nearly seven years, 2,124 of the women had developed breast cancer. What was obvious from the data is that smoking is terrible for the health of your mouth. Much of the risk for periodontal disease and some of the risk for cancer was determined simply based on whether or not a woman was a smoker or had been in the past. Both smokers and past smokers who had periodontal disease also seemed to have a higher risk of breast cancer, but when the full analysis was done, that relationship only held up for the past smokers. For those women with periodontal disease who had stopped smoking in the past 20 years, breast cancer cropped up 36 percent more often. Women with periodontal disease who had never smoked had a slightly higher risk or cancer at 6 percent, but that was significantly lower than if they had smoked.
It’s important to remember that these results don’t necessarily mean that gum disease is causing breast cancer. Smoking itself, for example, is known to cause gum disease, worsen overall oral health, and also contributes to a variety of cancers including breast cancer and this study confirms that link. But the study also highlights an apparent connection to periodontal disease showing that cancer and poor oral health may go hand in hand, especially when smoking is involved.
The authors suggested several explanations for this link. One is that bacteria from the mouth may enter the bloodstream and travel to breast tissue. The damage and inflammation they cause there could lead to cancer down the road. This is probably more likely to happen when the gums are bleeding, like during periodontal disease, since that means there’s an open door into the blood vessels bacteria can use to enter. Another possible explanation is that periodontal disease causes an inflammatory response throughout the body that might worsen chronic health problems like a cancer. More research is needed to pinpoint the exact mechanisms behind these oral-systemic connections and whether bacteria are actually behind some of these diseases or only a symptom of larger problems.
One limitation of this report is that the women’s periodontal disease was self-reported, rather than diagnosed by a dentist. That may mean some women said they had disease when they didn’t and others may have thought they didn’t have it when they actually did. Furthermore, since gum disease is often a sign of poor overall health, it is difficult to know if it’s the cause or just a symptom of worsening health that might signal the coming of a significant disease, like breast cancer. It is also important to note that overall oral health and smoking were both related to cancer in addition to periodontal disease, making clear that quitting smoking and taking good care of your health, including the health of your mouth, are probably two good ways you can lower your risk of cancer and oral health issues.
While more research is needed to understand the connection between breast cancer and gum disease, this study has shown that oral health is likely somehow related to breast cancer, and should spur further conversation on this topic.