‘Regular brushing and flossing of your teeth will help prevent cancers of the GI tract,’ is not a statement fully supported by the evidence—yet—but it seems only a matter of time before we get there.
A large-scale study conducted by the New York University School of Medicine and reported in JAMA last week, found that the presence of two oral bacterial pathogens increase your risk for cancer of the pancreas by a whopping 59 percent in the case of one of the bugs (Porphyromonas gingivalis), and by “at least” 50 percent in the case of the other (Aggregatibacter actionomycetemcomitans).
Pancreatic cancer is serious business because it’s typically discovered after it’s too late to do anything about it. In the US for example, less than 10% of those diagnosed will still be alive in 5 years, hence its high death toll of about 50,000 people annually.
Significantly, this JAMA-reported research does not stand alone. It builds on a growing body of evidence that links these periodontal disease-causing pathogens to pancreatic cancer. For example, JAMA also cites:
1) A European study that found P gingivalis associated with “a 2-fold greater risk of developing pancreatic cancer.”
2) A US study of 50,000 male health professionals that found “a history of periodontitis was associated with a 64% increased risk of developing pancreatic cancer.”
Notice a couple of things here:
One, why just the pancreas? To get to it, the bad bacteria in the mouth have to travel down the throat into the stomach then behind it to where the pancreas is attached, from where it secretes digestive enzymes into the stomach. So if the pancreas is affected by the bugs, shouldn’t the path leading to it from the mouth also be vulnerable to cancer? And what about the rest of the GI tract?
In short, the entire length of the GI tract, beginning with your mouth, has a periodontitis-driven elevated risk for cancer, according to a review of worldwide studies, published by PubMed 2 ½ years ago and available online here. Specifically, the review study found that cancers of the mouth, tongue, esophagus, digestive tract, colon, and prostate, are significantly elevated in those people with periodontal disease (a chronic inflammation of the gums) which, remember, is in turn driven by those bad bugs.
Two, bacteria (and viruses) are indeed linked to cancer as a causative agent and have been for years. For example, as the review study points out, Helicobacter pylori infection is linked with gastric cancer, Chlamydia pneumonia infection with lung cancer, Streptococcus bovis infection with colon cancer, and Salmonella Typhi to gall bladder cancer.
The big question, of course, is how: how do bad bugs drive cancer? Since we haven’t quite figured that out, these association studies (A is associated with B; the more A that you have, the more B you have) use carefully crafted words of non-causation such as “linked” to, and so on.
But don’t underestimate the power of these association studies, warns oncologist Sid Mukherjee MD, in his Pulitzer-prize winning book on cancer, The Emperor of all Maladies. Wherein he reminds us that for decades we had tobacco smoke “linked” to, “associated” with, and “correlated” with, various cancers. But it wasn’t until we were able to demonstrate how cancers are caused by tobacco smoke (by damaging our genes) that science began to use the c-word — causation — to describe the relationship between the two.
In fact, the PubMed review study suggests that bacteria also drive cancer by damaging our genes. They do so directly, and indirectly — via the chronic inflammation that is periodontitis — with the result that “Microorganisms [bacteria] and their products … may … induce mutations in the tumor-suppressor genes and proto-oncogenes,” thereby giving rise to cancers.
But we’re not quite there yet. In the meantime, the JAMA report observes, “although the NYU … study results are intriguing, it’s too soon to recommend that people step up their brushing and flossing as a preventive measure.” Maybe so, but until the verdict is in we might be cautioned to take our cue from Pascal’s Wager. The 17th C French philosopher Blaise Pascal argued that it’s best to live your life as if God exists because if you’re right, the reward is tremendous — you go to heaven; but if you’re wrong, there’s really no downside. Similarly, by living your life as if good oral hygiene can avoid a multitude of GI tract cancers, the reward is also tremendous — a healthy life; but even if you’re wrong, what’s the downside?