Beta blocker use and colorectal cancer risk

BACKGROUND: Recently, it has been postulated that long-term use of beta blockers might decrease the risk of certain types of cancer because of weakening of norepinephrine signaling. Previous studies on colorectal cancer (CRC) yielded inconsistent results, but lacked information on covariates. Thus, the authors investigated the association of beta blocker use and CRC risk in a large population-based case-control study (DACHS study). METHODS: Between 2003 and 2007, information on beta blocker use and potential confounders was collected by personal interviews for 1762 CRC cases and 1708 control individuals from Germany. The association of CRC risk and beta blocker use and subclasses of beta blockers was estimated by multiple logistic regression. In addition, site- and stage-specific analyses were performed. RESULTS: After adjustment for covariates, no association was observed with beta blocker use (odds ratio [OR], 1.05; 95% confidence interval [CI], 0.86-1.29) or with duration of beta blocker use. Also, the analysis by subclasses of beta blockers (cardioselectivity) and active ingredients (metoprolol, bisoprolol, carvedilol, and atenolol) or by CRC subsite showed no associations. In stage-specific analyses, long-term beta blocker use (6+ years) was associated with a significantly higher risk of stage IV CRC (OR, 2.02; 95% CI, 1.25-3.27). CONCLUSIONS: Our adjusted results do not support the hypothesis that beta blocker use is associated with decreased risk of CRC. In contrast, we found a positive association of long-term beta blocker use and risk of stage IV CRC. The latter result should be further evaluated in future studies.