Researchers have now claimed that medications commonly prescribed to treat high blood pressure may also reduce patients' colorectal cancer risk.

For our comprehensive coverage and latest updates on COVID-19 click here.

Angiotensin converting enzyme inhibitor (ACE-i) or angiotensin II receptor blocker (ARB) medications are prescribed for conditions such as heart failure, high blood pressure or heart disease. These medications inhibit or block angiotensin, a chemical that causes arteries to become narrow, the researchers said.

Doctors commonly prescribe these medications to people with high blood pressure to relax and open blood vessels, thereby lowering blood pressure. The current study, published in the Hypertension, an American Heart Association journal, revealed that taking these medications may also reduce colorectal cancer risk. "Our results provide new insights on a potential role of these medications for colorectal cancer prevention," said study author Wai K Leung from the University of Hong Kong in Hong Kong.

"This is the first study to show the potential beneficial effects of ACE inhibitors and ARBs on colorectal cancer development, based on a large group of patients who were colorectal cancer-free at the beginning of the study," Leung added.

The roles of ACE inhibitors and ARBs on cancer development are controversial and, in some cases, study findings are conflicting. Results of previous studies have been limited by several factors including a small number of patients and data only on short-term follow-ups. For the present study, the research team reviewed health records of 187,897 adult patients in Hong Kong from 2005 to 2013, with a negative baseline colonoscopy for colorectal cancer. The analysis found that those who took hypertension medications such as ACE-i or ARBs had a 22 per cent lower risk of developing colorectal cancer in the subsequent three years.

The benefits of ACE-i and ARBs were seen in patients 55 or older and those with a history of colon polyps and the benefit associated with the medications were limited to the first three years after the negative baseline colonoscopy. "While ACE-i and ARBs 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 anti-hypertensive medications," Leung said.

Researchers noted that the results should be verified with a prospective randomised controlled study, which would actively follow patients to determine the potential benefits of these medications on colorectal cancer risk.