Do Acid-Suppressing Medicines Cause Cancer?

Whether proton pump inhibitors (PPIs), medicines that reduce stomach acid, cause gastric cancer has been the subject of considerable scientific debate in recent years. A recent study, however, draws attention to the disputed and insufficient evidence for this association.

Do these medicines increase gastric cancer risk, or are people who already have a greater cancer risk more likely to use medicines that reduce stomach acidity?

Researchers arguing that PPIs may cause gastric cancer highlight their association with enterochromaffin-like cells, gastric atrophy, and changes in gastric mucosal immunology and gastric microflora. Opponents say these researchers overlook the possibility that the conditions or symptoms for which PPIs are prescribed may themselves be associated with cancer.

The Relationship Between Proton Pump Inhibitors and Gastric Cancer

Some researchers suggest that proton pump inhibitors (PPIs) cause gastric cancer, while others argue the opposite.

Associate Professor Daniele Piovani, from the Department of Medical Statistics at Humanitas University in Milan, Italy, says of the recent study discussed here: “Our findings are reassuring for all patients, particularly those with a reason for long-term PPI use who need sustained, effective gastric acid suppression to prevent serious health consequences.”

According to the article by Dr Piovani and colleagues in Alimentary Pharmacology and Therapeutics, published on 31 December 2022, earlier research did not account for the possibility that the conditions for which acid-suppressing medicines were prescribed could cause cancer.

Concern about PPIs’ potential to cause cancer arose after associations were found with enterochromaffin-like cells, gastric atrophy, and changes in the intestinal microbiota and gastric mucosal immunology. Observational studies and meta-analyses suggest a link between PPIs and increased gastric cancer risk. However, Dr Piovani says, “The underlying conditions for which PPIs are prescribed are associated with gastric cancer. This can result in an apparent association between PPIs and gastric cancer. ”

Another potential confounding factor is that PPIs are often initially used for symptoms of gastric cancer that has not yet been diagnosed.

“Consider a patient with a peptic (stomach) ulcer who takes a PPI. The person may not only have an ulcer but may also smoke heavily. Compared with a control patient without an ulcer who does not take a PPI, they may drink much more alcohol, have a different diet and be more likely to experience high levels of stress.”

No convincing evidence of an association with increased gastric cancer was found for either PPIs or other acid-suppressing medicines, such as famotidine (for example, Famodin).

Insufficient Evidence That PPIs Cause Gastric Cancer

Mark Lewis, Director of Gastrointestinal Oncology at Intermountain Healthcare in Murray, Utah, said, “I found this recent study relatively reassuring.”

Lewis said PPIs substantially increase stomach pH (in other words, reduce acidity) and try to heal the stomach through a process that can sometimes lead to tumours. However, these tumours appear benign. He said other concerns about PPI use, such as reduced bone density, were being investigated.

Lewis said some H2-receptor blockers, such as famotidine, might actually pose a greater cancer risk than PPIs, although many doctors now prefer PPIs as a newer generation of acid-suppressing medicines.

In conclusion The decision to use or avoid acid-reducing medicines such as PPIs should not be based on cancer risk. Patients who need to take them long term for medical reasons should feel reassured.