By Steven Reinberg
Women with gum disease appeared to have a 14 percent overall increased risk for breast cancer, compared to women without gum disease. And that increased risk seemed to jump to more than 30 percent if they also smoked or had smoked in the past 20 years, researchers said.
"These findings are useful in providing new insight into what causes breast cancer," said lead author Jo Freudenheim, a professor of epidemiology at the University at Buffalo's School of Public Health and Health Professions in New York.
"There is good evidence, though, that good dental care is important in any case and that treatment of periodontal disease is important for the health of the mouth," she said.
But more study is needed before there is enough evidence to say that gum disease causes breast cancer or other diseases, Freudenheim said. This study did not prove a cause-and-effect link between the two, a point made by several experts not involved with the study.
"There is much to learn about why we see these associations," she said. "In particular, we don't know yet if treating the gum disease would decrease risk of these other diseases."
The report was published Dec. 21 in the journal Cancer Epidemiology, Biomarkers & Prevention.
Dr. Ashish Sahasra, an orthodontist in Garden City, N.Y., said, "This is going to open a lot of people's eyes to the potential link between gum disease and breast cancer."
Periodontal disease can cause many health problems, he said. "Gum disease is very common, and sometimes it goes undiagnosed or misdiagnosed and many people don't pay attention to it, but it's a serious disease that needs to be treated immediately," he added.
For the study, Freudenheim and her colleagues collected data on nearly 74,000 postmenopausal women who took part in the Women's Health Initiative study. None of the women had a history of breast cancer. After an average follow-up of almost seven years, more than 2,000 women were diagnosed with breast cancer.
The researchers found that women who were smoking at the time of the study appeared to have a 32 percent higher risk for breast cancer if they had gum disease, but the association was not statistically significant, Freudenheim said, because there weren't many current smokers among the women in the study. Among women who had quit smoking sometime within the past 20 years, those with gum disease seemed to have a 36 percent higher risk of breast cancer.
In addition, women who had never smoked but had gum disease seemed to have a 6 percent increased risk of developing breast cancer, and those who had quit more than 20 years before and had gum disease had an 8 percent higher risk, the study suggested.
Dr. Stephanie Bernik, chief of surgical oncology at Lenox Hill Hospital in New York City, said, "Although there is a possibility that there is a direct link between gum disease and an increased risk of breast cancer, this study does not prove a direct link."
More study needs to be done to see if inflammatory factors such as gum disease contribute to the development of breast cancer, she said.
"Women with gum disease may lead lives that are less healthy overall, such as eating poorly, not exercising and drinking excessively," Bernik explained.
Dr. Leonard Lichtenfeld, deputy chief medical officer for the American Cancer Society, said, "We have to be cautious about putting too much emphasis on this study, but look at it in the context of overall health." Gum disease might be a sign of overall poor health and not the specific cause of breast cancer, he said.