ACE and colorectal cancer: Observational studies have found conflicting evidence on the association of ACE inhibitor use and colorectal cancer risk, for example; a large population-based case-control study (cases=15,560, controls=62,525) reported an increased risk of colorectal cancer (OR: 1.30, 95% CI: 1.22, 1.39) among long-term ACE inhibitor users (defined as 1000 daily doses within the past 5 years) as compared to age and gender matched controls (39).