Background: Studies suggest that tooth loss and periodontal disease might increase the risk of developing various cancers; however, smoking might have confounded the reported associations. We aimed to assess whether periodontal disease or tooth loss is associated with cancer risk.
Methods: The analysis was done in a prospective study (the Health Professionals Follow-Up Study [HPFS]), which was initiated in 1986 when US male health professionals aged 40-75 years responded to questionnaires posted by the Department of Nutrition, Harvard University School of Public Health, Boston, MA, USA. In addition to the baseline questionnaires, follow-up questionnaires were posted to all living participants every 2 years and dietary questionnaires every 4 years. At baseline, participants were asked whether they had a history of periodontal disease with bone loss. Participants also reported number of natural teeth at baseline and any tooth loss during the previous 2 years was reported on the follow-up questionnaires. Smoking status and history of smoking were obtained at baseline and in all subsequent questionnaires. Additionally at baseline, participants reported their mean frequency of food intake over the previous year on a 131-item semiquantitative food-frequency questionnaire. Participants reported any new cancer diagnosis on the follow-up questionnaires. Endpoints for this study were risk of total cancer and individual cancers with more than 100 cases. Multivariate hazard ratios (HRs) and 95% CIs were calculated by use of Cox proportional hazard models according to periodontal disease status and number of teeth at baseline.
Findings: In the main analyses, 48 375 men with median follow-up of 17.7 years (1986 to Jan 31, 2004) were eligible after excluding participants diagnosed with cancer before 1986 (other than non-melanoma skin cancer, n=2076) and those with missing data on periodontal disease (n=1078). 5720 incident cancer cases were documented (excluding non-melanoma skin cancer and non-aggressive prostate cancer). The five most common cancers were colorectal (n=1043), melanoma of the skin (n=698), lung (n=678), bladder (n=543), and advanced prostate (n=541). After adjusting for known risk factors, including detailed smoking history and dietary factors, participants with a history of periodontal disease had an increased risk of total cancer (HR 1.14 [95% CI 1.07-1.22]) compared with those with no history of periodontal disease. By cancer site, significant associations for those with a history of periodontal disease were noted for lung (1.36 [1.15-1.60]), kidney (1.49 [1.12-1.97]), pancreas (1.54 [1.16-2.04]; findings previously published), and haematological cancers (1.30 [1.11-1.53]). Fewer teeth at baseline (0-16) was associated with an increase in risk of lung cancer (1.70 [1.37-2.11]) for those with 0-16 teeth versus those with 25-32 teeth. In never-smokers, periodontal disease was associated with significant increases in total (1.21 [1.06-1.39]) and haematological cancers (1.35 [1.01-1.81]). By contrast, no association was noted for lung cancer (0.96 [0.46-1.98]).
Interpretation: Periodontal 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 periodontal disease might be a marker of a susceptible immune system or might directly affect cancer risk.