The use of drugs such as H2 blockers and proton pump inhibitors reduce stomach acid . This was believed to increase the risk of cancer of the esophagus or stomach . Common H2 blockers are ranitidine (Zantac) and cimetidine (Tagamet); and a common proton pump inhibitor is omeprazole (Prilosec).

A new finding says that H2 blockers and proton pump inhibitors do not increase the risk of cancer of the esophagus or stomach, but cancer risk is probably due to other related factors.'There have been concerns regarding the safety of long-time gastric acid suppression,' senior investigator Dr Mats Lindblad said.'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 his colleagues at the Karolinska Institute in Stockholm studied 7 years of patient data gathered in the UK general practice database.

287 patients with esophageal cancer and 522 with stomach cancer were identified. They were compared with 10,000 randomly selected subjects who were not affected by cancer.

The authors identified specific conditions for which acid-suppressing drugs are used, such as acid reflux disease, hiatal hernia and Barrett's esophagus,and which were associated with an increased risk of stomach and esophagus cancer.

Whereas, no cancer risk was seen with other conditions, including peptic ulcer, gastritis, and indigestion. They found no evidence to show that drugs themselves increased the risk.

These findings are similar to results from previous studies, continued Lindblad. The inference is that the cancer risk may be due to underlying conditions, and not an independent, harmful effect of these drugs.

In an interview, Dr Kenneth E L McColl, author of an accompanying editorial, agreed with him. McColl of the Western Infirmary, Glasgow, UK says 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'.