Proton pump inhibitor use linked to elevated cancer risk

GENEVA — Exposure to proton pump inhibitors appeared associated with increased risk for certain cancers, according to results of a meta-analysis presented at World Cancer Congress.

The elevated risk appeared independent of duration of proton pump inhibitor exposure.

Proton pump inhibitors often are used to treat various gastrointestinal disorders.

Prior observational studies have suggested a potential association between use of these agents and development of cancer; however, results have been inconsistent.

Tien Hoang Tran, student at National Cancer Center Graduate School of Cancer Science and Policy in the Republic of Korea, and colleagues conducted a meta-analysis of cohort studies to calculate the pooled cancer risks among individuals exposed vs. not exposed to proton pump inhibitors.

Investigators searched PubMed and EMBASE from inception through March of this year to identify relevant cohort studies that examined this association.

Two reviewers independently screened search results to confirm eligibility and extracted relevant data. If they found data on the same cancer type reported in more than one study, the reviewers selected the study that included the most comprehensive data.

Researchers excluded studies that were not published in peer-reviewed journals, published in English, or only presented at conferences.

Tran and colleagues used the Newcastle-Ottawa Scale for cohort studies to assess the quality of studies included in the primary analysis, and they used the Egger’s regression test to assess publication bias.

The analysis included 15 cohort studies with a combined 5.2 million individuals.

Results showed a statistically significant increased risk for cancer among individuals exposed to proton pump inhibitors (HR = 1.22; 95% CI, 1.02-1.46; I2 = 85.4%).

A subgroup analysis that examined specific cancer types revealed significant associations between proton pump inhibitor use and gastric cancer (HR = 1.56; 95% CI, 1.08-2.26; I2 = 82.4%) and liver cancer (HR = 1.48; 95% CI, 1.15-1.9; I2 = 50.6%). However, researchers observed no association with colorectal cancer (HR = 1.15; 95% CI, 0.85-1.54; I2 = 88.9%).

Researchers observed no association between cancer risk and proton pump inhibitor use longer than 1 year (HR = 1.27; 95% CI, 0.76-2.12, I2 = 80.8%).

Beyond the overall class effect for proton pump inhibitors, investigators reported significant associations between cancer risk and use of lansoprazole (HR = 1.65; 95% CI, 1.11-2.47; I2 = 59%) and omeprazole (HR = 1.51; 95% CI, 1.06-2.14; I2 = 41.7%).