RAAS inhibitor use may reduce 3-year colorectal cancer risk in certain patients
Use of renin-angiotensin-aldosterone system, or RAAS, antagonists such as ACE inhibitors or angiotensin receptor blockers was linked to reduced risk for colorectal cancer in the 3 years after an index colonoscopy with negative diagnosis.
For every year of ACE inhibitor or angiotensin receptor blocker use, researchers observed a 5% decrease in risk for colorectal cancer, up to 3 years.
“While ACE inhibitors and angiotensin receptor blockers are taken by patients with high blood pressure, heart failure and kidney diseases, the reduction in colorectal cancer risk may be an additional factor for physicians to consider when choosing antihypertensive medications,” Wai K. Leung, MD, clinical professor of medicine at the University of Hong Kong, said in a press release.
For the retrospective cohort study published in Hypertension, researchers assessed patients aged at least 40 years who had undergone a colonoscopy between 2005 and 2013 (n = 187,897; 49% men; 21% with prior colonic polyps; 17% on ACE inhibitors/angiotensin receptor blockers) with the goal of observing the association between colorectal cancer risk and the use of ACE inhibitors or angiotensin receptor blockers. The primary outcome was colorectal cancer diagnosis at 6 to 36 months after colonoscopy.
3-year risk reduction
Of the overall cohort, 0.45% developed colorectal cancer 6 to 36 months after index colonoscopy, according to the study.
Researchers found that use of ACE inhibitors or angiotensin receptor blockers was associated with decreased risk for colorectal cancer within 3 years after index colonoscopy (adjusted HR = 0.78; 95% CI, 0.64-0.96), but not after more than 3 years (aHR = 1.18; 95% CI, 0.88-1.57).
“While colorectal cancer and hypertension are both common diseases, this is the first study to show that the use of ACE inhibitors or angiotensin receptor blockers, common medications used for treating hypertension, are associated with a lower risk of colorectal cancer after having a normal colonoscopy,” Leung told Healio. “The benefit was particularly strong for patients older than 55 years and those with history of colonic polyps, in whom the risks of colorectal cancer are higher. Interestingly, the risk was restricted to those cancers that developed within 3 years after colonoscopy, but not more than 3 years.”
Duration of drug use and cancer risk
In other findings, the risk for developing colorectal cancer in the 3 years following negative coloscopy diagnosis shrank with each year of ACE inhibitor or angiotensin receptor blocker use (aHR = 0.95; 95% CI, 0.91-0.99).
Patients with at least 2 years of ACE inhibitor/angiotensin receptor blocker use had a greater magnitude of reduced risk for colorectal cancer compared with patients with no use (aHR = 0.77; 95% CI, 0.6-0.97) than did patients with less than 2 years of ACE inhibitor/angiotensin receptor blocker use (aHR = 0.85; 95% CI, 0.63-1.14), the researchers wrote.
“Apart from side effects and contraindications, compelling indication is another factor to be considered in the choice of a particular antihypertensive medication,” Ka Shing Cheung, MBBS, MPH, MRCP, FHKCP, FHKAM, of the department of medicine at the University of Hong Kong, Queen Mary Hospital, and colleagues wrote. “Our study provided additional insights into the potential chemopreventive effects of ACE inhibitors/angiotensin receptor blockers against colorectal cancer development, apart from their known cardiovascular and renal benefits.”