Getting Into the Data: In Depth On Oral Bacteria and Cancer

Last week we put up several links to studies that show a pretty clear link between oral bacteria and cancer. We couldn't help but think that perhaps it would be helpful to some of you if we translated at least one of them from scientific jargon into layman's English. From The Journal of Oral Microbiology:

"Inflammation caused by infections may be the most important preventable cause of cancer in general. However, in the oral cavity the role of microbiota in carcinogenesis is not known. Microbial populations on mouth mucosa differ between healthy and malignant sites and certain oral bacterial species have been linked with malignancies but the evidence is still weak in this respect. Nevertheless, oral microorganisms inevitably up-regulate cytokines and other inflammatory mediators that affect the complex metabolic pathways and may thus be involved in carcinogenesis. Poor oral health associates statistically with prevalence of many types of cancer, such as pancreatic and gastrointestinal cancer."

What this says, in short, is that many cancers are indirectly caused by infections -- indirectly because it's not the infection itself that causes the cancer, but instead the inflammation caused when your body fights the infection. In addition, this is inflammation that certain bacteria in your mouth can make much, much worse. We haven't figured out exactly how these bacteria cause cancer, so we can't say for certain that they do -- but the statistical correlation between oral health and cancer risk is quite significant.

"Our unpublished results from a cohort study in Sweden with 16 years of follow-up showed that age, female gender, and periodontitis with loss of the first mandibular molars were the principal independent predictors of cancers in general, and breast cancer in particular, as registered in the Swedish Cancer Registry. From the same database, premature death of young individuals was observed to link statistically with periodontitis and missing molars whether the cause of death was because of cancer, cardiovascular, or gastrointestinal disease."

This is the quote we referred to in this months' newsletter. Translated, it says that there are three factors that are the most correlated with breast cancer. The first is the age of the person. The second is their gender. The third is whether or not they had periodontal disease when their first molars were removed.

Why is this considered just as relevant as age and gender? Because it's statistically correlated to an extraordinary degree; if you had periodontal disease when your first molars came out, you were much more likely to get breast cancer. It’s not quite the difference between getting breast cancer as a man and getting breast cancer as a woman, but close to the difference between getting it as a 25 year old and getting it as a 35 year old.