Study links acid reflux, esophageal cancer.

The human esophagus gets its share of irritation. Stomach acid bubbling up into this tube often inflames it, resulting in the misnamed but familiar problem of heartburn. An acid-blocking pill or antacid usually seems to take care of the difficulty.

Researchers, however, have asked whether such chronic inflammation can lead to more serious trouble. Prolonged irritation has been shown to disrupt cell growth. For example, steady inflammation of the liver from hepatitis has been linked to liver cancer. New data suggest a similar risk for the esophagus.

Heartburn, or acid reflux, is more common in patients diagnosed with a cancer called adenocarcinoma of the esophagus than it is in healthy people, Swedish researchers report in the March 18 New England Journal of Medicine. While the study doesn't prove that acid reflux causes cancer, chronic irritation presents "one potential mechanism" for it, says study coauthor Jesper Lagergren, a gastrointestinal surgeon and epidemiologist at the Karolinska Institute in Stockholm.

Esophageal adenocarcinoma is quite rare. Seeking a link with heartburn, Lagergren and his colleagues compared 820 healthy people with 189 patients who had recently been diagnosed with this cancer. The participants had an average age of almost 70.

The researchers found that 60 percent of the cancer patients had had acid reflux at least once a week for 5 years or more, compared with only 16 percent of the control group. While 3 percent of the controls reported acid reflux more than 3 times a week, 22 percent of the cancer patients did. Likewise, 3 percent of the controls reported reflux going back more than 20 years, compared with 21 percent of the cancer patients.

"This is one of those studies that confirms what everyone believes," says David Y. Graham, a gastroenterologist at Baylor College of Medicine and the Veterans Affairs Medical Center, both in Houston.

Researchers haven't ascertained how the cancer develops. The link connecting heartburn and cancer may be a syndrome called Barrett's esophagus, a precancerous condition in which the lining of the lower esophagus is replaced by cells that resemble stomach-lining cells, says Graham.

Previous studies indicated that about 10 percent of heartburn sufferers have Barrett's esophagus. Although only about 1 percent of people with Barrett's esophagus develop esophageal cancer in any given year, it's still considered a risk factor. Most people with esophageal adenocarcinoma have had Barrett's esophagus.

In the Swedish study, 62 percent of the patients with esophageal adenocarcinoma had signs of Barrett's. The actual correlation may be much higher because by the time cancer is diagnosed, tumors may have overtaken and obscured the Barrett's lesions, says Henry P. Parkman of Temple University School of Medicine in Philadelphia.

The new study indicates that people seeking treatment for chronic heartburn might benefit from being tested for Barrett's esophagus, Parkman adds, so that those who have the condition could be screened for adenocarcinoma.