Aspirin's Cancer Prevention Gap

2026-10-11

Prevention has a prescription gap. Aspirin remains rarely used to prevent colorectal cancer in people with Lynch syndrome, despite randomized evidence that this inexpensive medicine can reduce their risk. Evidence alone changes little. The disconnect exposes a stubborn problem in medicine: a treatment can earn its place in research without securing one in routine care.

The benefit deserves attention. In the CAPP2 trial, 861 participants with Lynch syndrome were assigned to aspirin or placebo, with the aspirin group receiving 600 milligrams daily. Protection was not immediate. Extended follow-up found roughly a 40 percent reduction in colorectal cancer incidence among those assigned aspirin, although the trial dose should not be read as a universal prescription. Biology explains the stakes. Lynch syndrome involves inherited defects in DNA mismatch repair, allowing genetic errors to accumulate and raising susceptibility to colorectal, endometrial and several other cancers. Mechanisms remain under investigation. Aspirin inhibits cyclooxygenase enzymes, but its cancer-preventive effects may involve additional pathways that researchers have not fully resolved.

Underuse is not automatically negligence. Gastrointestinal bleeding, ulcer history, interacting medicines and uncertainty over the best dose complicate decisions, while evidence from hereditary cancer populations cannot simply be extended to everyone. Screening still has work. Aspirin does not replace colonoscopic surveillance, and patients should discuss suitability and dosing with a clinician rather than begin treatment themselves. Better conversations are overdue. For a person facing inherited cancer risk, the distance between a published result and an informed choice can be measured in an unopened medicine cabinet.

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