Gum disease: A cancer risk factor
PEOPLE who have periodontal (gum) disease may have a higher risk of developing some forms of cancer, suggests a letter published in the journal Gut, detailing a prospective study.
American researchers found that a history of periodontal disease appeared to be associated with a raised risk of oesophageal (gullet) and gastric (stomach) cancer.
This risk was also higher among people who had previously lost (permanent or adult) teeth.
Previous findings on the relationship between periodontal disease and tooth loss, and oesophageal and gastric cancer have been inconsistent.
Therefore, a team of researchers from the Harvard T.H. Chan School of Public Health in Boston, carried out a study of patient data over decades of follow-up.
They examined the association of periodontal disease and tooth loss history with the risk of oesophageal and gastric cancer in 98,459 women from the Nurses’ Health Study (1992-2014) and 49,685 men from the Health Professionals Follow-up Study (1988-2016).
Dental measures, demographics, lifestyle and diet were assessed using follow-up questionnaires and self-reported cancer diagnosis was confirmed after reviewing medical records.
The results showed that during 22 to 28 years of follow-up, there were 199 cases of oesophageal cancer and 238 cases of gastric cancer.
A history of periodontal disease was associated with a 43% and
52% increased risk of oesophageal cancer and gastric cancer respectively.
Compared to people with no tooth loss, the risks of oesophageal and gastric cancer for those who lost two or more teeth were also modestly higher – 42% and 33% respectively.
In addition, among individuals with a history of periodontal disease, no tooth loss and losing one or more teeth were equally associated with a 59% increased risk of oesophageal cancer, compared to those with no history of periodontal disease and no tooth loss.
Similarly, the same group of individuals had 50% (no tooth loss) and 68% (loss of one or more teeth) greater risk of gastric cancer respectively.
The authors point to an association between oral bacteria and oesophageal and gastric cancer as a possible reason, with evidence from other studies suggesting that Tannerella forsythia and Porphyromonas gingivalis were associated with the presence or risk of oesophageal cancer. Both bacterium are members of the “red complex” of periodontal pathogens, which is associated with severe forms of periodontal disease.
Another possible reason is that poor oral hygiene and periodontal disease could promote the formation of endogenous nitrosamines known to cause gastric cancer through nitrate-reducing bacteria.
This was an observational study, so no firm conclusions can be drawn about cause and effect.
The researchers also cannot rule out the possibility that some of the observed risk may be due to other unmeasured (confounding) factors.
However, they conclude: “Together, these data support the importance of oral microbiome in oesophageal and gastric cancer.
“Further prospective studies that directly assess the oral microbiome are warranted to identify specific oral bacteria responsible for this relationship.
“The additional findings may serve as readily accessible, noninvasive biomarkers and help identify individuals at high risk for these cancers.”