Associations of angiotensin-converting enzyme inhibitor or angiotensin receptor blocker use with colorectal cancer risk in the women⇔s health initiative

Background: Use of angiotensin-converting enzyme inhibitors (ACEi) and angiotensin receptor blockers (ARB) has been postulated to reduce cancer risk by inhibition of tumor progression, vascularization, and metastasis. The renin–angiotensin system is upregulated in colorectal cancers; however, the association of ACEi and ARB use with colorectal cancer risk is not well understood. Methods: The study population was 142,812 Women’s Health Initiative participants free of colorectal cancer who reported on ACEi and ARB use at baseline; 2,216 incident colorectal cancers were diagnosed during 10 years of follow-up. Cox regression models estimated adjusted HRs and 95% confidence intervals for associations relative to nonuse among normotensive women, untreated hypertensive women, and hypertensive women treated with other antihypertensive medications. Results: HRs among women who used any ACEi or ARB compared with nonuse in the three referent groups ranged between 0.97 and 1.01. Findings were similar for increased ACEi/ARB duration and for medications examined as separate classes or individually. Conclusions: In this large prospective study of women, no associations of ACEi or ARB use with colorectal cancer risk were observed. Impact: Choice of drug in the large population of aging women who will be prescribed ACEi and ARB should be made without factoring in any benefit on colorectal cancer risk.