A bacterial species responsible for gum disease, Porphyromonas gingivalis, has been demonstrated to be present in cancerous tissue of 61% of patients with esophageal squamous cell carcinoma (ESCC).
This conclusion is the result of collaborative research between scientists from the University of Louisville School of Dentistry (KY, USA) and the College of Clinical Medicine of Henan University of Science and Technology (Luoyang, China).
The results of the study, recently published in the journal Infectious Agents and Cancer, indicate that P. gingivalis is present in only 12% of tissues adjacent to the cancerous cells. In addition to this, P. gingivalis was not detected in normal esophageal tissue.
“These findings provide the first direct evidence that P. gingivalis infection could be a novel risk factor for ESCC, and may also serve as a prognostic biomarker for this type of cancer,” explained author Huizhi Wang of the University of Louisville School of Dentistry. “These data, if confirmed, indicate that eradication of a common oral pathogen may contribute to a reduction in the significant number of people suffering with ESCC.”
The study sample consisted of 100 individuals with ESCC and 30 controls. The researchers measured the expression of lysine-gingipain, an enzyme unique to P. gingivalis, as well as the presence of the bacterial cell DNA within the esophageal tissues.
Levels of lysine-gingipain and bacterial cell DNA were significantly higher in the cancerous tissue of ESCC patients than in surrounding tissue or normal control sites. The presence of P. gingivalis correlated with other factors, including cancer cell differentiation, metastasis and overall survival rate.
Wang proposes two possible explanations for the observed results; one being that ESCC cells are a preferred niche for P. gingivalis to thrive, the other that P. gingivalis infection facilitates the development of esophageal cancer.
If it is proven that ESCC cells are a preferred niche for P. gingivalis, Wang indicates that antibiotics may provide a useful treatment or researchers can develop other therapeutic approaches for esophageal cancer utilizing genetic technology to target the P. gingivalis and ultimately destroy the cancer cells.
“Should P. gingivalis be proven to cause ESCC, the implications are enormous,” Wang explained. “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 the Centers for Disease Control, approximately 15,000 individuals are diagnosed with esophageal cancer each year in the United States. Esophageal cancer is difficult to diagnose at an early stage and is characterized by rapid progression and high mortality.