I have been hearing for years how taking aspirin daily would prevent this or that type of cancer. I admit to confusion on the issue. There always seemed to be new qualifiers to the statement. So, I was thrilled to see an interview with Eric J. Jacobs, Ph.D., American Cancer Society (ACS) Researcher on the ACS website.
A. Yes, there is now definitive evidence that long-term daily aspirin use, even at low doses, will lower risk of developing one type of cancer – colorectal cancer, probably by approximately 40%. However, this benefit is unlikely to “kick in” immediately. There appears to be a delay of several years between when aspirin use is started and when risk of developing colorectal cancer is reduced.
It is also important to realize that aspirin can have serious side effects, which may outweigh its favorable effects on colorectal cancer risk. Therefore the American Cancer Society does not recommend using aspirin specifically to prevent cancer. More evidence about other types of cancers is needed.
Q. Are there certain types of cancers for which the evidence is stronger?
A. Besides colorectal cancer, there is very strong evidence that aspirin use lowers risk of developing cancer of the esophagus, and fairly strong evidence that aspirin use lowers risk of developing stomach cancer. These two cancers are not among the most common in the U.S., but they are of some importance because they tend to be very hard to treat.
For other cancers, the evidence is less clear. Some studies suggest that aspirin users are at 10% to 20% lower risk of developing certain other cancers, including two of the most common, breast cancer and prostate cancer. The new study in the Journal of the National Cancer Institute adds to the evidence that aspirin might modestly lower risk of ovarian cancer. However, other studies have found no effect. None of these studies are randomized trials, the most reliable type of study, where people are randomly assigned to take either aspirin or a placebo pill.
The bottom line on taking aspirin, according to Dr. Jacobs is, “At this point, neither the American Cancer Society, nor any other health organization, recommends taking aspirin specifically to help prevent cancer. People who are wondering if they should take aspirin should talk to their own health care provider, who knows their individual medical history and is aware of other medications they may be using, and can take this into account when weighing the risks and benefits of aspirin use.”