Overview
- The Cochrane synthesis pooled 10 randomized trials (124,837 average‑risk adults) comparing aspirin with placebo or no treatment, with no suitable non‑aspirin NSAID trials.
- Across 5–15 years of follow‑up, aspirin showed little or no reduction in colorectal cancer or adenoma incidence.
- Trial data signaled a possible increase in colorectal cancer mortality at 5–10 years, while suggested benefits beyond 15 years remained uncertain due to follow‑up biases.
- Daily aspirin increased serious extracranial bleeding and probably raised hemorrhagic stroke risk, with higher doses carrying greater harm.
- Authors advise against starting aspirin solely for cancer prevention in the general population, urging clinician‑patient discussions; established cardiovascular uses for secondary prevention remain in place.