Joint US/UK study links periodontal disease with several cancers 

A large prospective cohort study has revealed a link between gum disease and the risk of developing cancer, reports the June issue of Lancet Oncology. The study, undertaken in male health professionals, showed that participants with periodontal disease had a 14 % increased risk of cancer compared with volunteers without periodontal disease. For individual cancer sites, lung, pancreas and kidney cancers were found to be associated with periodontal disease.

Gum or periodontal disease is an infection of the tissues surrounding and supporting the teeth. Prior studies have suggested that people with periodontal disease are more likely to develop heart disease, stroke and diabetes. Indeed, one study showed that infections with Porphyromonas gingivalis, accelerate atheroma (fat) deposition in animal arteries.

People with gum disease have increased concentration of inflammatory markers in their blood, and inflammation also has been linked with cancer. But the association could simply mean that whatever causes the inflammation might independently cause gum disease and cancer.

Dominique Michaud and colleagues from Imperial College, London, UK, undertook the study to investigate possible associations between gum disease and cancer by analysing data from the Health Professionals Follow-Up study (HPFS). This was a study that started in 1986 and targeted 51,529 American male health professionals aged between 40 and 75 years, with participants including dentists, vets, pharmacists, optometrists, osteopathic physicians and podiatrists. Using health professionals allowed subjects to be “fairly homogenous” with respect to education and socio economic status, write the authors.  In addition to information on smoking history and food intakes the survey, which was managed by the Harvard University School of Public Health, USA,  asked  participants  to report on baseline gum disease with bone loss, number of natural teeth, and tooth loss in the previous two years. Follow-up questionnaires collected data on any new cancer diagnoses every two years, with dietary questionnaires issued every four years.

Results showed that 40,512 participants had no history of periodontal disease, while 7,863 did.  During an average follow-up of 17.7 years, 5,720 cancer cases were reported. These cases excluded non-melanoma skin cancer and non-aggressive prostate cancer.

The five most common cancers were colorectal (1,043 cases), melanoma of the skin (698 cases), lung (678), bladder (543), and advanced prostate (541). After adjusting for details about the history of smoking, dietary factors, and other known risk factors, researchers found that participants with a history of gum disease were 14% more likely to develop any type of cancer compared to those without history of gum disease. Furthermore, results showed that compared to men with healthy gums, men with a history of gum disease were 49% more likely to develop kidney cancer, 36% more likely to develop lung cancer, 54% more likely to develop pancreatic cancer and 30% more likely to develop hematological cancers (including non-Hogdkin’s lymphoma, leukemia, and multiple myeloma).  But when taken individually only non-Hodgkin’s lymphoma reached significance.

Additional analyses found a 70% increase in the risk of lung cancer for patients who had less than 16 teeth at baseline, compared to individuals who had between 25 and 32 teeth. In people who have never smoked, gum disease was predicted to increase their overall cancer risk by 21% and their risk of blood cancers by 35%.

Dr Michaud and colleagues said the findings of the study need confirmation, but suggest that periodontal disease might be either a marker of a susceptible immune system or might directly affect cancer risk. “We believe that further research on the role of periodontal disease in cancer, especially haematological cancers, is warranted,” write the authors, adding that at this stage any recommendations for prevention of cancer based on periodontal health would be premature. “Patients with periodontal diseases should seek care from their dentists irrespective of the effect on cancer,” they say.

The study is limited by self-reports of periodontal disease and by inadequate power to study less common cancers, the researchers said. Also, since the study was undertaken solely in men, the findings might not apply to women.