By: Diana Barnes-Brown for Reflux1The link between acid reflux disease (GERD) and cancer has been noted by researchers for some time now, but the reason why this connection exists has continued to puzzle medical practitioners hoping to reduce cancer risks for reflux sufferers.
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Call your doctor immediately if you notice any of the following symptoms of esophageal cancer:
Difficulty or pain when swallowing
Weight loss
Feeling of food or drink being stuck in the throat
Throat or back pain, or pain behind breastbone or between shoulder blades
Hoarseness, coughing, and loss of voice
Vomiting or gagging
Coughing up blood
Talk with your doctor about a possible GERD diagnosis if you notice any of these symptoms:
Persistent heartburn
Acid regurgitation or “burping up” acidic stomach secretions
Chest pain
Morning hoarseness
Difficulty swallowing; sensation of tightness or of something being stuck in throat
Dry cough
Bad breath |
Now, new research completed by researchers from Brown University and published in the Journal of Biological Chemistry has helped to identify the mechanism by which GERD may encourage the growth of cancer cells. The researchers found that cancer cells are higher in a particular enzyme when exposed to acid. This exposure may lead to an overproduction of hydrogen peroxide, which begins to explain how GERD factors into esophageal cancer rates. Senior author Weibiao Cao, a researcher at Rhode Island Hospital and an assistant professor of medicine and surgery at Brown Medical School, and his team investigated the effects of acid on the enzyme NOX5-S. They found that acid causes the cells to undergo stress, and activates genes in a way that causes DNA damage. Further, they were able to trace the signaling pathway from acid-damaged cells to the onset of esophageal cancer. Thus, cells exposed to the acid that is characteristic of GERD appear to be susceptible to dangerous changes.
Cao noted that “the role of acid is controversial. But we know that by exposing cells to acid for short periods of time, a particular enzyme is affected, triggering a chain of events that possibly leads to cancer of the esophagus.” He added that with this improved understanding, researchers “can possibly identify who is at risk of developing cancer by determining the levels of this enzyme.”
The team used human cancer cells and biopsies from patients with the pre-cancerous condition Barrett’s esophagus (BE), where the cells in the esophagus have been altered by their exposure to digestive acids. They found that the enzyme NOX5-S is present in much greater quantities in esophageal tissues of patients with Barrett’s esophagus. Continued acid exposure leads to an increase in calcium in esophageal cells, activating a chemical chain of events that leads to increased cell growth and decreased cell death. In other words, a cancer-favorable environment is fostered.
When the researchers removed the enzyme NOX5, acid-induced hydrogen peroxide production was reduced, and when calcium was removed, NOX5 was reduced and hydrogen peroxide production decreased. By experimenting with these very specific chemical changes, the researchers were able to demonstrate the sequence by which Barrett’s esophageal cancer cells develops. If researchers can determine how to block NOX5 production, new therapies for those susceptible to or in the early stages of cancer of the esophagus can be developed.
Patients with esophageal cancer traditionally have poor prognoses, with median survival rates of less than 18 months from the time of diagnosis. Five-year survival rates for patients with esophageal cancer are less than 20 percent after surgery. The largest risk factor for this type of cancer is GERD.
If you have GERD, especially if it is chronic, talk to your doctor about getting an endoscopy to see if you have Barrett’s esophagus. Physicians often prescribe acid-blocking drugs and periodic cancer screening if results are positive.
