Gum disease linked to cancer risk

Oesophageal and gastric cancers are more common among those with poor oral health, new research finds.

Gum disease increases the risk of oesophageal and gastric cancers, a prospective study suggests.

The findings lend weight to the theory that oral health is linked to overall health. This link between gum, or periodontal, disease and these cancers has been hinted at by previous research  but the findings have been inconsistent.

Dr Mingyang Song, associate professor of clinical epidemiology and nutrition at Harvard University, and his colleagues undertook a prospective study of 150,000 participants from both the Nurses’ Health Study and the Health Professionals Follow-up Study.

They used follow-up questionnaires to collect information on demographics, dental health, diet and lifestyle, comparing these data with self-reported cancer diagnosis, confirmed by medical records.

Researchers found individuals with gum disease were 43% more likely to develop oesophageal cancer and 52% more likely to develop gastric cancer than their peers without periodontal disease.

The likelihood of these cancers was also moderately increased in those individuals who had lost two or more teeth. Participants with this degree of tooth loss were 42% more likely to develop oesophageal cancer and 33% more likely to develop gastric cancer than their peers who had not lost teeth.

Having a history of gum disease and either no tooth loss or only one lost tooth both increased the risk of oesophageal cancer by 59%, compared to those with healthy gums and teeth.

Similarly, a history of gum disease but no tooth loss was tied to a 50% increase in gastric cancer, and a 68% increase for those who had also lost one tooth, according to the research letter published in the journal, Gut.

“Increasing evidence has highlighted the strong scientific rationale for a link between oral microbiome and oesophageal and gastric cancer,” wrote Dr Song.

The pathogens Tannerella forsythia and Porphyromonas gingivalis were both part of a group known as the “red complex” of periodontal pathogens, he wrote, and had been linked to oesophageal cancer in previous research.

People with gastric cancer have also been shown to have more T. forsythia and other microbes in their mouths.

“Poor oral hygiene and periodontal disease could also promote the formation of endogenous nitrosamines known to cause gastric cancer through nitrate-reducing bacteria,” he added.

More research needed to be undertaken to identify specific microbes responsible for the cancer risk, and these findings could give clinicians easy and non-invasive biomarkers to identify patients at a high risk, Dr Song said.

“Together, these data support the importance of oral microbiome in oesophageal and gastric cancer. Further prospective studies that directly assess oral microbiome are warranted to identify specific oral bacteria responsible for this relationship.”

Gut 2020, 20 July