BUFFALO, N.Y., May 22 -- An increased risk of tongue cancer in men has been associated with chronic periodontitis, independent of smoking status, researchers here reported.
Each millimeter of alveolar bone loss was associated with a more than fivefold increase in the risk of tongue cancer, reported Mine Tezal, D.D.S., Ph.D., of the Roswell Park Cancer Institute, and colleagues, in the May issue of the Archives of Otolaryngology Head and Neck Surgery.
The mean alveolar bone loss in these men was more than a third higher in cancer cases compared with controls, they found in a small study.
Considerable evidence indicates that chronic infections and persistent inflammation are associated with increased cancer risk, Dr. Tezal said.
Although periodontitis is a chronic oral infection thought to be caused by Gram-negative anaerobic bacteria, recent evidence also suggests a significant role for viruses in the start and progression of periodontitis, Dr. Tezal added.
To assess this association, the researchers compared 51 non-Hispanic white men newly diagnosed with primary squamous-cell carcinoma of the tongue, and 54 non-Hispanic white men evaluated during the same period but without a malignancy.
They were treated from 1999 to 2005. Periodontitis was assessed by alveolar bone loss measured from panoramic radiographs by one examiner blind to cancer status. Tongue cancer diagnoses came from the Roswell Park tumor registry.
The mean alveolar bone loss was significantly higher in cancer cases compared with controls (4.21 mm versus 2.74 mm; P
In this study information on alcohol use, smokeless tobacco, and diet was not available. In addition, smoking history was not quantitative and no information on time since quitting smoking was available.
However, the researchers said, the observed association in never-smokers, suggests that the observed relationship between periodontal disease and tongue cancer is independent of smoking.
How infection and inflammation can influence carcinogenesis has interested scientists for more than a century, but only now are the general principles emerging, the researchers said.
Chronic infections, such as periodontitis, can play a direct or indirect role, they wrote.
For example, as a direct toxic effect, periodontal viruses and bacteria and their products (endotoxins or enzymes, for example) are toxic to surrounding cells and may directly induce mutations in tumor suppressor genes and proto-oncogenes or alter signaling pathways that affect cell proliferation or survival of epithelial cells.
There may also be an indirect effect through inflammation, they suggested. Chronic infection may stimulate the formation of epithelial-derived tumors through an indirect mechanism involving activation of surrounding inflammatory cells.
This association between a history of periodontitis and the risk of tongue cancer, they said, needs to be confirmed by larger studies that include other oral cancer sites, women, those of other races, and a quantitative assessment of lifetime tobacco exposure.