Statins reduce the progression of non-advanced adenomas to colorectal cancer: a postcolonoscopy study in 187 897 patients

Background and aims Postcolonoscopy colorectal cancer (PCCRC) accounts for up to 9% of all CRCs. Statins have been shown to be associated with a lower CRC risk. We aimed to investigate whether PCCRC risk was also lower among statin users. Methods This is a retrospective cohort study using a territory-wide electronic healthcare database in Hong Kong including patients aged 40 years or above who had undergone colonoscopies between 2005 and 2013. Exclusion criteria included prior colorectal cancer (CRC), inflammatory bowel disease, prior colectomy and CRC detected within 6 months of index colonoscopy. We defined statin use as at least 90-day use before index colonoscopy. Medication use was traced up to 5 years before index colonoscopy. PCCRC-3y was defined as cancer diagnosed between 6 and 36 months after index colonoscopy. Sites of CRC were categorised as proximal (proximal to splenic flexure) and distal cancer. The subdistribution HR (SHR) of PCCRC-3y with statin use was derived by propensity score matching based on covariates (including patient factors, concurrent medication use and endoscopy centre's performance). Results Of 187 897 eligible subjects, 854 (0.45%) were diagnosed with PCCRC-3y. Statin use was associated with a lower PCCRC-3y risk (SHR: 0.72; 95%CI 0.55 to 0.95; p=0.018). Subgroup analysis shows that SHRs were 0.50 (95% CI 0.28 to 0.91; p=0.022) for proximal and 0.80 (95% CI 0.59 to 1.09; p=0.160) for distal cancer. Older (>60 years) patients, women and those without diabetes mellitus or polyps appeared to benefit more from statins. Conclusions Statins were associated with a lower PCCRC risk, particularly for proximal cancer.