A new study recommends chemoprevention with aspirin to curb the development of colorectal cancer in Lynch syndrome carriers, whom are at higher risk for the disease due to a genetic defect.

Researchers at Newcastle University (United Kingdom) conducted a randomized, placebo-controlled study of aspirin involving 937 carriers of Lynch syndrome who were randomized to four groups; high-dose aspirin (600 mg/day) plus resistant starch placebo; resistant starch (30 g) plus aspirin placebo; aspirin plus resistant starch; and aspirin placebo plus starch placebo. At initial analysis, following a mean 29 months of treatment, the results suggested that aspirin or resistant starch, or both, did not reduce the risk of colorectal neoplasia. There was a nonsignificant reduction in colorectal neoplasia in the aspirin group (8%), compared with the non-aspirin group (11%).

But, as previous studies have indicated the need for extended follow-up to reveal a reduced risk of colorectal cancer, the researchers prespecified a double-blind long-term follow-up in the postintervention period. At a mean follow-up of 55.7 months, 48 of the 861 participants randomized to aspirin or aspirin placebo had developed 53 primary colorectal cancers. Intention-to-treat analysis of time to first colorectal cancer showed a hazard ratio (HR) of 0.63 and an incidence rate ratio (IRR) of 0.56. For participants completing 2 years of intervention, per-protocol analysis yielded an HR of 0.41 and an IRR of 0.37. The results indicate that 600 mg aspirin daily for a mean of 25 months reduced cancer incidence by 60% in carriers of hereditary colorectal cancer after long term follow-up. The study was published early online on October 28, 2011, in the Lancet.

“Our results, taken in conjunction with recent research, provide a basis for recommendation of aspirin chemoprevention in Lynch syndrome as standard of care,” concluded lead author John Burn, MD, and colleagues. “Further studies are needed to establish the optimum dose and duration of aspirin treatment.”

Lynch syndrome involves loss-of-function mutations in a DNA mismatch repair gene. While the mutations are rare, approximately 80% of individuals with them will develop colorectal cancer eventually. The cancers that develop in Lynch syndrome patients also tend to develop at an earlier age than sporadic tumors.

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