[Risk for developing tumors in therapy with the proton pump inhibitor omeprazole]

The experience received hitherto with the treatment of omeprazole proves this drug as absolutely save and poor of side effects. ECL-cell hyperplasia and carcinoids which occur during application of very high doses of omeprazole in rats are not caused by a direct effect of omeprazole. These changes are induced by extremely elevated serum gastrin levels due to achlorhydria. However, these high doses of omeprazole are not applicated in man. Therefore, the results from animal studies can not be applied on humans. During long-term treatment with omeprazole in most patients only slight increases of serum gastrin levels and ECL-cell densities occur. Only a very few patients exhibit a progressive and marked increase of serum gastrin levels. These patients should be carefully monitored by endoscopy in regularly intervals. There is no current evidence to support the contention that omeprazole is genotoxic. Results from Burlinson on the potential of omeprazole to induce DNA damage proved to be unsounded and of no clinical relevance. Omeprazole produced negative results in all well established genotoxicity tests. The incidence of neoplasias in the stomach is not increased after long-term acid suppression as indicated by 15 years application of H2-blockers and even a longer period of experience with vagotomy. Hitherto, there is also no evidence that acid inhibition induced by omeprazole causes an increased rate of carcinoma of the stomach. The risk for promoting carcinomas of the colon by the mild hypergastrinaemia during treatment with omeprazole seems to be inferior. In addition the correlation between development of carcinomas of the colon respective rectum and hypergastrinaemia is discussed controversly.