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    A medium size clinical trial has shown that taking a daily aspirin (81mg) can substantially reduce the occurrence of advanced colorectal adenomas as well as a less but still significant reduction in non-advanced adenomas. One peculiar thing about the trial is that at a higher dose (325mg) of aspirin the benefit is not there. Also, it is known that this regime requires up to 10 years of daily aspirin to see an effect, and even then, once the aspirin stops there is no lingering protective effect. This 10 year treatment requirement may be a reason why this trial did not find a protection in using the higher dose since this particular trial went for 3 years. The following review provides excellent insight into not only colorectal cancer benefits but a general cancer chemopreventive (chemical protection) effect of aspirin.

    There is extensive background on the mechanisms involved in aspirin’s possible protection against cancer. There is also great discussion on other non-steroidal anti-inflammatory drugs (NSAIDs). NSAID is a class of drugs that has pain-relief and anti-inflammation properties but is not of the steroid molecular structure. Aspirin, Ibuprofen, Naproxen, and Celecoxib are a few. The main effect of NSAIDs is to block the COX1 and COX2 enzymes that are responsible for making various molecules that signal the body to produce the inflammation response. Celecoxib is part of a class called COXibs that affects the COX2 enzyme specifically. One notorious COXib is rofecoxib (Vioxx) which was taken off the market after clinical trials showed an increased risk of cardiovascular problems. Even though aspirin is used as a treatment to prevent heart attacks and stroke, it inhibits both COX enzymes while the COXibs affect the COX2 enzyme. This is now thought to alter a balance between the products of the two COX enzymes, leading to cardiovascular toxitcity.

    This review is very well balanced in that it touts the possible benefits of the use of NSAIDs but cautions on the side effectsterm and toxicities for some individuals. For example, it has been shown that people with certain mutations in the COX enzymes show no benefit from taking aspirin while for other people, the daily dose of aspirin can cause bleeding and ulceration of the digestive tract, since constant inhibition of the COX enzyme doesn’t allow for the production of some molecules that have beneficial effects. That is why it is imperative that before giving aspirin or other NSAIDs as a chemopreventive, the benefits should outweigh the risks and side effects in the individual.

This is the abstract for the article on prevention of colorectal cancer with aspirin. The full article is also posted.