Aspirin has been linked to a reduced risk of developing colorectal cancer in previous studies.  It is thought that the impact of aspirin may come through its inhibition of the enzyme cyclooxygenase-2 (COX-2) which is overexpressed in many colorectal cancers.  A team at Massachusetts General Hospital and Harvard Medical School has now shown that aspirin also helps survival in patients who have already got colorectal cancer and, indeed, also reduces overall mortality.

They looked at the long-running Health Professionals Follow-up Study and also the Nurses’ Health Study, identifying a group of 1,279 men and women who had colorectal cancer and provided information on aspirin use.  Follow up was around 12 years, during which time there were 193 total deaths (35%) and 81 (15%) deaths from colorectal cancer among those who used aspirin regularly after their cancer diagnosis.  The figures for those who did not use aspirin were 287 total deaths (39%) and 141 (19%) deaths from colorectal cancer.  Five year survival for aspirin users was 88% and 83% for non-aspirin users. At ten years, these rates were 74% and 69%.

Regular use of aspirin after diagnosis was linked to 29% lower risk of death from colorectal cancer overall, with an even higher reduction in those with grade II or grade III cancer, which carry a bigger risk.  The benefit, however, was confined to those whose tumors overexpressed COX-2, where aspirin acts, and to those who took up aspirin after cancer was diagnosed.  The study is not suggesting that all those who have colorectal cancer should now start on aspirin – further, well-designed prospective studies are needed before this can be recommended.  The study opens up the possibility of tailoring aspirin use to those whose colorectal tumors are positive for COX-2 overexpression.

Source

Chan A, Ogino S and Fuchs C Aspirin use and survival after diagnosis of colorectal cancer Journal of the American Medical Association August 12 2009;302:649-658