Brushing, flossing, and regular dental checkups appear to do much more than maintain a healthy smile. Now, a large prospective cohort study shows that postmenopausal women with a history of periodontal disease, including those who have never smoked, are at significantly increased overall risk for cancer as well as site-specific cancers, including lung, breast, esophageal, gallbladder, and melanoma skin cancers.
"Ours is the first study to report on the association between periodontal disease and gallbladder cancer risk in women or men," say Jean Wactawski-Wende, PhD, from the State University of New York at Buffalo, and colleagues in an online report published August 1 in Cancer Epidemiology, Biomarkers & Prevention.
The study authors note that these results add to the growing body of evidence from smaller studies and studies in men that link periodontal disease to total cancer risk.
"Optimal oral hygiene is important in preventing tooth loss but may have important implications for prevention of systemic diseases, including cancer," Dr Wactawski-Wende told Medscape Medical News.
"Periodontal disease is preventable, manageable, and in many cases, treatable," she emphasized, adding "it may be prudent for clinicians to advise all their patients to maintain good oral health. Men and younger women may consider these findings potentially relevant to them as well."
The Centers for Disease Control and Prevention (CDC) estimate that 47% of adults 30 years of age and older in the United States have some form of periodontal disease, ranging from mild to severe. At age 65 years and older, however, 70% of adults have moderate to severe periodontal disease, according to the CDC.
Total Cancer Risk Increased by 14%
The study involved almost 66,000 postmenopausal women in the United States, who were enrolled in the ongoing Women's Health Initiative Observational Study (WHI-OS). During a mean follow-up of 8.32 years, the team identified 7149 cancers and found that periodontal disease history was associated with a 14% increased total cancer risk, with a multivariable-adjusted hazard ratio (HR) of 1.14.
When analyses were limited to 34,097 never-smokers, there was also an increased risk for overall cancer (HR, 1.12).
An association between periodontal disease and site-specific cancers was observed in breast (HR, 1.13), lung (HR, 1.31), esophageal (HR, 3.28), gallbladder (HR, 1.73), and melanoma skin (HR, 1.23) cancers.
There was a borderline association with stomach cancer (HR, 1.58), the study authors report, and periodontal disease was not associated with cancers of the pancreas; liver; lower digestive tract organs; or lip, oral cavity, and pharynx combined. Similarly, there was no association with genitourinary and lymphoid and hematopoietic malignancies.
"Our findings support the need for further understanding of the effect of periodontal disease on cancer outcomes," Dr Wactawski-Wende and colleagues say.
Previous studies have shown that periodontal disease is a risk factor for breast cancer, oral, and esophageal cancers, and case-control studies have demonstrated an association between tooth loss — a proxy for periodontal disease — and risk for esophageal and stomach cancers, the study authors note.
However, few studies have analyzed the overall risk for all types of cancers, although the mechanisms behind the association between periodontal disease and cancer remain unclear. "Intervention studies that include treatment of periodontal disease may be warranted to determine if cancer risk can be reduced overall or in specific high-risk sites," the authors suggest.
Although periodontal disease and cancer share important risk factors, such as increased risk with increasing age and increased risk in smokers, this study showed that after adjustment for age, the risk for periodontal disease history and cancer persists regardless of smoking history, Dr Wactawski-Wende pointed out.
For the study, the investigators looked at periodontal disease information in 65,869 women aged 54 to 86 years at 40 US centers. Mean age was 68 years. Most women were non-Hispanic whites with some college education.
All participants answered the question "Has a dentist or dental hygienist ever told you that you had periodontal or gum disease? (No/Yes)" between 1999 and 2003 on the annual Year-5 WHI-OS follow-up questionnaire. Cancer outcomes were documented through September 2013 with a maximum 15-year follow-up period.
Women who reported a history of periodontal disease were also more likely to report a history of smoking, secondhand smoke exposure, alcohol use, hormone therapy (estrogen plus progestin), and a cancer diagnosis, the study authors report. At the same time, no significant differences were observed in body mass index, physical activity levels, or history of diabetes between women with periodontal disease and those without.
Because classification by smoking status "can create fuzzy boundaries" in a cohort study, there may have been incomplete control for the effect of smoking and bias estimates of periodontal disease, the study authors admit. However, they attempted to "tease that out" by examining never-smokers with a history of periodontal disease. In that group, the association between periodontal disease and the risk for total cancer remained unchanged and statistically significant, they say.
This work was supported by the National Institutes of Health, the US Department of Health and Human Services, and the US Army, Medical Research and Materiel Command, Fort Detrick. Dr Wactawski-Wendehas disclosed no relevant financial relationships. One study coauthor reports relationships with Cigna, Colgate Palmolive, and Sunstar. The other authors have disclosed no relevant financial relationships.
Cancer Epidemiol Biomark Prev. Published online August 1, 2017.