People with gum disease have higher cancer risk

People who have gum disease have a higher overall cancer risk, an association which is found in both smokers and non-smokers. These are the conclusions of authors of an Article published in the June edition of The Lancet Oncology.

Individuals with gum infections have increased concentrations of circulating inflammatory markers in their blood. However, uncertainty surrounds whether or not systemic inflammation, pathogenic invasion into the bloodstream, or the immune response to gum infection might have an effect on cancer risk overall, or at various tumour sites. Dr Dominique Michaud, Imperial College London, UK, and colleagues aimed to explore this association.

The researchers used data from the Health Professionals Follow-Up study (HFPS) which began in 1986 when US male health professionals aged 40-75 years responded to questionnaires posted by Harvard University, USA. In addition to baseline questionnaires, follow-up questionnaires were sent to all living participants every two years, and dietary questionnaires every four years. Baseline gum disease with bone loss, number of natural teeth, and tooth loss in previous two years were recorded, as was smoking history and food intake. Participants reported any new cancer diagnosis on the follow-up questionnaires. Endpoints measured were overall cancer risk and individual cancers with more than 100 cases.

A total of 48375 men, with a median follow-up of 17.7 years were eligible for this study. Within these individuals, 5720 cases of incident cancer were recorded (excluding non-melanoma skin cancer and non-aggressive prostate cancer). The five most common cancers were colorectal (1043), melanoma of the skin (698), lung (678), bladder (543) and advanced prostate (541). After adjustment for known risk factors, including detailed smoking and history and dietary factors, participants with a history of gum disease had a 14% higher risk of cancer compared with those with no history of gum disease.

For individual cancer sites, those with a history of gum disease had an increased risk of lung cancer (36%), kidney (49%), pancreas (54%), and haematological (white blood cell) cancers (30%), compared with those with no history of gum disease. Fewer teeth at baseline (0-16) was associated with a 70% increased risk of lung cancer compared with individuals with 25-32 teeth at baseline. In never-smokers, gum disease was associated with a 21% increase in overall cancer risk, and a 35% increased risk of blood cancers. By contrast, no association was noted for lung cancer.

The authors conclude: "Gum disease was associated with a small, but significant, increase in overall cancer risk, which persisted in never-smokers. The associations recorded for lung cancer are probably because of residual confounding by smoking. The increased risks noted for haematological, kidney, and pancreatic cancers need confirmation, but suggest that gum disease might be a marker of a susceptible immune system or might directly affect cancer risk."

Dr Michaud is in Switzerland from 23-28 May but she can be reached via the Imperial College London Press Office on +44 (0)20 7594 6702, or via email at d.michaud@imperial.ac.uk