Long-term ranitidine use ups bladder cancer risk

Use of ranitidine in the long term appears to increase the risk of bladder cancer, reveals a large population-based study.

“Ranitidine has been shown to contain the carcinogen N-nitrosodimethylamine and increase urinary N-nitrosodimethylamine in humans,” the authors said. “We [then] investigated whether ranitidine use is associated with increased bladder cancer risk.”

This nested case-control study was conducted within the Primary Care Clinical Informatics Unit Research database containing general practice records from Scotland. The authors diagnosed bladder cancer cases between 1999 and 2011 and matched these with up to five controls based on age, sex, general practice, and date of registration.

Using prescribing records, ranitidine was identified along with other histamine-2 receptor agonists and proton pump inhibitors (PPIs). Conditional logistic regression was used to calculate odds ratios (ORs) and 95 percent confidence intervals (CIs) after adjusting for comorbidities and smoking.

A total of 3,260 patients and 14,037 controls were included. Compared with nonusers, ranitidine users had an increased risk of bladder cancer (fully adjusted OR, 1.22, 95 percent CI, 1.06–1.40). This risk is more prominent among users for over 3 years (fully adjusted OR, 1.43, 95 percent CI, 1.05–1.94).

On the other hand, evidence was scarce on any association between PPI use and bladder cancer risk based on any use (fully adjusted OR, 0.98, 95 percent CI, 0.88–1.11) or over 3 years of use (fully adjusted OR, 0.98, 95 percent CI, 0.80–1.20).

“Further studies are necessary to attempt to replicate this finding in other settings,” the authors said.