Aspirin for prevention of colorectal cancer is controversial.
Dr Catherine Dubé and colleagues examined the benefits and harms of aspirin chemoprevention.
The team evaluated the Cochrane Collaboration's registry of clinical trials and searched the Cochrane Database of Systematic Reviews.
There were 2 independent reviewers who conducted multilevel screening to identify randomised trials, case-control, and cohort studies of aspirin chemoprophylaxis.
The team searched systematic reviews for adverse outcomes.
The researchers abstracted data in duplicate, and assessed quality.
|Aspirin was associated with a 22% reduction in colorectal cancer risk|
|Annals of Internal Medicine|
The researchers found that regular use of aspirin reduced the incidence of colonic adenomas in randomized, controlled trials, case-control, and cohort studies.
In cohort studies, regular use of aspirin was associated with relative risk reductions of 22% for incidence of colorectal cancer.
The team found that 2 randomized, controlled trials of low-dose aspirin failed to show a protective effect.
The researchers reported that data for colorectal cancer mortality were limited.
The team observed that benefits from chemoprevention were more evident when aspirin was used at a high dose, and for periods longer than 10 years.
Aspirin use was associated with a dose-related increase in incidence of gastrointestinal complications.
Dr Dubé's team concluded, “Aspirin appears to be effective at reducing the incidence of colonic adenoma and colorectal cancer, especially if used in high doses for more than 10 years.”
“However, the possible harms of such a practice require careful consideration.”
“Further evaluation of the cost-effectiveness of chemoprevention compared with, and in combination with, a screening strategy is required.”