Aspirin and cancer risk: a quantitative review to 2011

Aspirin and cancer risk: a quantitative review to 2011:

Background:
Aspirin has been associated to a reduced risk of colorectal and possibly of a few other common cancers.

Methods:
To provide an up-to-date quantification of this association, we conducted a meta-analysis of all observational studies on aspirin and 12 selected cancer sites published up to September 2011.

Results:
Regular aspirin is associated with a statistically significant reduced risk of colorectal cancer and of other digestive tract cancers, for squamous cell esophageal cancer, for esophageal and gastric cardia adenocarcinoma,, for gastric cancer), with somewhat stronger reductions in risk in case–control than in cohort studies. Modest inverse associations were also observed for breast and prostate cancer, while lung cancer was significantly reduced in case–control studiesbut not in cohort ones. No meaningful overall associations were observed for cancers of the pancreas, endometrium, ovary, bladder, and kidney.

Conclusions:
Observational studies indicate a beneficial role of aspirin on colorectal and other digestive tract cancers; modest risk reductions were also observed for breast and prostate cancer. Results are, however, heterogeneous across studies and dose–risk and duration–risk relationships are still unclear.