Dental plaque associated with 'premature' cancer death

Poor oral hygiene, reflected by dental plaque, was associated with increased cancer mortality in a Swedish study, published online today in BMJ Open.

After taking into account other risk factors, dental plaque was associated with a significant 79% increased risk for premature death from cancer.

The study was conducted by Birgitta Söder, PhD, and colleagues from the Department of Dental Medicine at the Karolinska Institute in Huddinge, Sweden, in collaboration with researchers from the University of Helsinki in Finland.

The researchers note that a high amount of dental plaque indicates poor oral hygiene and an increased risk for dental infections. In turn, these could trigger systemic reactions and lead to malignant transformations in a variety of tissues.

"The high bacterial load on tooth surfaces and in gingival pockets over a prolonged period of time may indeed play a role in carcinogenesis," they speculate.

However, the researchers emphasize that their findings do not prove that dental plaque causes or definitely contributes to cancer.

Assessment of Mouth Hygiene
The 1390 study participants were randomly selected in Stockholm; they were in their 30s and 40s when the study began, and had no signs of periodontitis. They completed a questionnaire about risk factors for cancer, including smoking, and they underwent a mouth hygiene check to assess levels of dental plaque, tartar, gum disease, and tooth loss.

The absolute risk for premature death was low; only 58 of the 1390 study participants were no longer alive when the study ended after 24 years. Of those who died, 35 died from cancer. Breast cancer was the most common type of cancer in women; the malignancies in men were varied.

When the researchers looked at the mouth hygiene results, they found that participants who had died had more dental plaque than the those who had survived. The dental plaque index, which indicates how much of the tooth is covered in plaque, was consistently higher in those who died from cancer than in the survivors (0.84 to 0.91 vs 0.66 to 0.67; P < .001).

In this study, the average age at death was 60 years for women and 61 years for men. According to demographic data for Sweden, the women should have lived another 13.0 years and the men another 8.5 years, so these deaths could be considered "premature," the authors note.

In addition to the presence of dental plaque, the other risk factors that significantly increased the risk for premature death were sex and age. Nearly two thirds of all those who died were men.

This same team of researchers showed an association between periodontal disease and breast cancer, with an odds ratio of 2.36 (Breast Cancer Res Treat. 2011;127:497-502), and previously reported that an association between periodontitis and missing teeth increased the risk for premature death from life-threatening disease, including cancer (J Periodontal Res. 2007;42:361-366).

A recent review article, which included these and other studies, asked whether oral and dental disease are linked to cancer (Oral Dis. 2011;17:779-784). Those authors conclude that "evidence in the literature remains inadequate to allow final conclusions to be drawn on whether infectious diseases of the mouth are a true risk factor for the development of malignancies. Some epidemiological data indicate an association but no causal relationship has been established."

Source: http://www.medscape.com/viewarticle/765436?sssdmh=dm1.793222&src=nldne