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Study Finds Zantac Increases Gastrointestinal Cancer Risk By Over Three Times

Study Finds Zantac Increases Gastrointestinal Cancer Risk By Over Three Times

A study by the University of Alabama published on December 23 found that Zantac increased gastrointestinal cancer risk by 3.66 times compared to other heartburn drugs.

The study sought to evaluate the association between exposure to ranitidine, which Zantac contains, and gastrointestinal cancer by utilizing a comparison group minimizing confounding by indication. The researchers selected 141,963 events reported to the FDA Adverse Events Reporting System associated with the use of H2 antagonists and proton pump inhibitors (PPIs).

“In conjunction with a large body of epidemiologic and human and animal basic science research, the study results support the hypothesis that NDMA-contaminated ranitidine increases the risk of cancer and supports the withdrawal of these medications from the market,” the researchers found.

The researchers selected 13,856 adverse event reports for ranitidine monotherapy. The most common indications for ranitidine were dyspepsia (37.5%) and gastroesophageal reflux disease (21.2%).

The researchers found that the proportion of adverse events for gastrointestinal cancers, including pharyngeal, esophageal, stomach, colorectal, liver and pancreatic cancers was 3.66 times the proportion seen in PPIs and H2 antagonists.

“The results of the current study supported the interpretation that NDMA is carcinogenic in humans, specifically to the gastrointestinal system,” the researchers wrote.

The researchers note the study is unique in that it compares cancer occurrence in ranitidine users to the occurrence in a group using drugs to treat similar conditions. The researchers note previous studies have compared Zantac users to non-users who have a low prevalence of underlying conditions which are associated with an increased cancer risk.

“By comparing ranitidine users to users of PPIs and other H2 antagonists, the current study was better able to reduce the impact of confounding by indication and thereby isolate the role of NDMA,” the researchers wrote.

“The relationship between NDMA exposure and gastrointestinal cancer is biologically plausible; in fact, the evidence for this relationship is substantial,” the researchers wrote, adding, “the formation (in the case of endogenous NDMA), absorption, distribution, metabolism, and excretion of NDMA primary involves the organs of the gastrointestinal system, thereby placing them at risk for cancer induction via exposure to pathways that cause DNA damage.”

The researchers note they found the strongest association between ranitidine use and colorectal cancer.

“The results of the current study provided direct support for the assertion that NDMA contaminated ranitidine is associated with the occurrence of gastrointestinal cancer,” the researchers concluded, stating this assertion “was bolstered by an abundance of evidence demonstrating that NDMA exposure is associated with an increased risk of cancer in humans as well as animals.”


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