Blocking stomach acid doesn't raise cancer risk

NEW YORK (Reuters Health) - Overall, the use of drugs that reduce stomach acid, such as H2 blockers and proton pump inhibitors, do not increase the risk of cancer of the esophagus or stomach, according to a study reported in the journal Gut.

Common H2 blockers are ranitidine (Zantac) and cimetidine (Tagamet); and a common proton pump inhibitor is omeprazole (Prilosec).

"There have been concerns regarding the safety of long-time gastric acid suppression," senior investigator Dr. Mats Lindblad told Reuters Health. "I think our large study clearly suggests that long-time gastric acid suppression does not increase the risk" of cancer of the esophagus or stomach.

Lindblad and colleagues at the Karolinska Institute in Stockholm evaluated 7 years of patient data entered into the UK general practice database. The team identified 287 patients with esophageal cancer and 522 with stomach cancer. These subjects were compared with 10,000 randomly selected subjects without cancer.

The authors found some conditions for which acid-suppressing drugs are used, such as acid reflux disease, hiatal hernia and Barrett's esophagus, were associated with an increased risk of stomach and esophagus cancer. However, no apparent cancer risk was seen with other conditions, including peptic ulcer, gastritis, and indigestion. They found no evidence that the drugs themselves increased the risk.

These findings are in line with those of previous studies, continued Lindblad. The new information is that the cancer risk is probably due to underlying conditions, rather than an independent, harmful effect of these drugs.

In an interview with Reuters Health, Dr. Kenneth E.L. McColl, author of an accompanying editorial, agreed that the findings are consistent with such a conclusion.

However, McColl of the Western Infirmary, Glasgow, UK added that "a major weakness in the study is the relatively short duration of acid suppressive therapy examined. The development of cancer in humans is a slow process."

The period in question "is really too short to identify or exclude any direct effect between acid suppressive medication and" stomach or esophageal cancers.

SOURCE: Gut, November 2006.