Gum disease bacteria linked to esophageal cancer risk

Study shows a causal relationship between specific bacterial infections and the development of esophageal cancer

Esophagus is a muscular tube that is instrumental in movement of food from mouth to the stomach. It is lined with two kinds of cells and hence there are two main types of esophageal cancer- Adenocarcinoma and Squamous cell carcinoma, the latter being more common in developing countries.

This type of cancer progresses rapidly and has a high mortality rate. Like other cancers, the number of risk factors include chemical exposure, diet, heredity and age- however it is still difficult to diagnose this cancer early!

Now, a team of researchers from University of Louisville School of Dentistry have made a surprising causal finding in which they found that a bacteria found in the mouth and that is responsible for gum disease, Porphyromonas gingivalis is present in 61% of the cancerous tissues in patients with esophageal squamous cell carcinoma (ESCC).

Furthermore, only 12% of tissues adjacent to the cancerous cells showed the presence of P. gingivalis while it remained undetected in normal esophageal mucosa.

This was confirmed by immunohistochemistry studies on tissue samples from 100 patients with ESCC and 30 normal controls. By measuring the expression of an enzyme called lysine-gingipain, that is unique to P. gingivalis, as well as the presence of the bacterial cell DNA within the esophageal tissues, they detected the presence of these bacteria.

What are the possible implications if this is true? It suggests that P. gingivalis infection could be a novel risk factor for ESCC and may also serve as a biomarker that would help us detect this type of cancer early on.

“Should P. gingivalis prove to cause ESCC, the implications are enormous,” says Huizhi Wang, M.D., Ph.D.,  assistant professor of oral immunology and infectious diseases at the UofL School of Dentistry.

“It would suggest that improving oral hygiene may reduce ESCC risk; screening for P. gingivalis in dental plaque may identify susceptible subjects; and using antibiotics or other anti-bacterial strategies may prevent ESCC progression.”

According to Wang, there are two likely explanations: Either the cancer cells prefer an environment rich in P. gingivalis to thrive or the bacteria facilitates the development of esophageal cancer. If the former is true, simple antibiotics may prove useful or researchers can develop other therapeutic approaches for esophageal cancer utilizing genetic technology to target the P. gingivalis and ultimately destroy the cancer cells, says Wang.

It should be remembered that only a causal relationship has been suggested in this study, still a lot more studies need to be done to prove that P. gingivalis can cause ESCC.

The findings were published in Infectious Agents and Cancer

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