Aspirin prevents colorectal cancer in those with increased genetic risk
MedWire News: Long-term aspirin use reduces colorectal cancer incidence by around 60% in people genetically predisposed to the condition, researchers report in The Lancet.
All patients included in the Colorectal Adenoma/carcinoma Prevention Programme (CAPP)2 study were carriers of Lynch syndrome, also known as hereditary non-polyposis colon cancer, which puts them at high risk for developing colorectal cancer and a range of other solid organ cancers.
Lead author John Burn (Newcastle University, UK) and colleagues write that more than two decades of observational data show that the risk for colorectal cancer is substantially reduced in regular aspirin consumers, but no randomized controlled aspirin trials have employed prevention of colorectal cancer as a primary endpoint.
To address this, the team set up the CAPP2 trial, in which carriers of Lynch syndrome were randomly assigned to receive aspirin 600 mg per day (n=434) or placebo (n=427) for at least two years.
Initial analysis after a mean of 29 months on treatment showed no significant difference in colorectal cancer incidence between those who had taken aspirin and those who had not.
However, the current long-term follow-up data at a mean of 56 months showed that there were significantly fewer new colorectal cancers among the participants in the aspirin group than among those in the placebo group, at 19 versus 34. This corresponds to a 44% reduced incidence of colorectal cancer among patients who received aspirin.
When the researchers focused on patients who had been taking aspirin or placebo for 2 years or longer (around 60% of all participants), they found that colorectal cancer incidence was 63% lower in those taking aspirin compared with those on placebo, with 23 cases in the placebo group but only 10 in the aspirin group.
Kaplan-Meier analysis revealed that the effect of aspirin became evident 5 years after patients starting taking the drug.
Of note, Burn and team also observed a nonsignificant reduction in other cancers associated with Lynch syndrome, including cancer of the endometrium and womb.
The researchers conclude that their results, taken in conjunction with recent research, "provide a basis for recommendation of aspirin chemoprevention in Lynch syndrome as standard of care."
They add that their next trial, CAPP3, "will seek to establish the optimum dose and duration of aspirin treatment."
In a statement to the press Burn cautioned: "Before anyone begins to take aspirin on a regular basis they should consult their doctor as aspirin is known to bring with it a risk of stomach complaints including ulcers.
"However, if there is a strong family history of cancer then people may want to weigh up the cost-benefits particularly as these days drugs which block acid production in the stomach are available over the counter," he concluded.
In a linked comment, Andrew Chan (Harvard Medical School, Boston, Massachusetts, USA) and Scott Lippman (University of Texas MD Anderson Cancer Center, Houston, USA) agree that the results provide "strong rationale" for routine use of aspirin in individuals with Lynch Syndrome.
"Unfortunately, prohibitive logistics make a randomized trial of aspirin prevention with a colorectal cancer endpoint in a sporadic-risk population unlikely. Therefore, these results from CAPP2 and previous evidence arguably support more general recommendations to consider aspirin for prevention of colorectal cancer in the context of individualized risk-benefit assessments," they conclude.
By Laura Dean