Aspirin’s Effect on Colorectal and Gastrointestinal CancersOctober 25th, 2013
by Rebecca Kyper, Cedarville University PharmD Student
We are all familiar with aspirin, a common over the counter, nonsteroidal anti-inflammatory drug (NSAID). Aspirin is used to treat pain, fever, and it is used for preventive heart health. The effect of aspirin on certain types of cancers has been studied for a few years, especially in colon cancer and esophageal cancer. One study found that aspirin significantly decreased deaths from colorectal cancer (P=.003).1 Another study presents significant findings about aspirin reducing the risk of gastric cancer (P =.02).2 Yet another study found statistically significant data (P=.001) that aspirin reduces the risk of esophageal cancer.3 There are other studies with these types of findings that show aspirin can help with gastric cancers. US News online reported on a new study that attempts to explain why this effect has been observed in the literature.4
This article briefly describes the findings of a new study that claims aspirin may lower the rate of DNA mutation in the GI tract. The study consisted of thirteen patients with Barrett’s esophagus, which often progresses into esophageal cancer.4 They tested mutations in tissue samples collected by these patients, and compared the mutation rates with the amount of aspirin the patients had taken.4 Although they saw a reduction in the mutation rates of those patients who were on aspirin compared to those who were not, the data was not statistically significant.4 The researchers plan on investigating this further in attempt to find more data. They theorize that DNA mutations will be reduced because of the anti-inflammatory action of aspirin.4
This study is interesting and reports findings that have built groundwork for more research to be done to explore this possibility. The article presents a very positive view, which may be premature for the study. The study had a few limitations that must be factored into the results. The first limitation is that there was no statistically significant conclusion (the article states that there was no cause-effect relationship found) made from their data. With no statistical significance found, it is hard to be positive about the promising results of the study because these effects could be from outside variables. The sample size was only thirteen patients, which decreases the statistical power and generalizability of these findings. It would be very helpful to increase the amount of patients in additional studies. These limitations lead to a more careful review of the study, but I do not think they negate the possibility that future research could produce more conclusive results.
The literature on the effects of aspirin on DNA mutation is limited; however, one study suggests other mechanisms for aspirin’s apparent effects on gastric cancers. This study found that aspirin has an effect on NFkB signaling and apoptosis of cells (cell death), and this is what contributes to its preventative effects.5 This study could play a role in the direction the new studies will take. If aspirin shows evidence of increasing the rate of cell apoptosis, this could be tied to lowering the rate of DNA mutation. However, this does not mean that aspirin would directly affect DNA mutation. Another study showed that aspirin may reduce the risk of certain types of cancers by suppressing a mutation phenotype.6 This study also had information and research on the apoptosis that is caused by aspirin, and about how aspirins effect could be tied more directly with DNA. 6 All of these studies encourage further research to be done to explore aspirin’s effects on gastric cancers in depth.
The prior research about the effects of aspirin on specific types of cancers would be reason to pursue the ideas presented by the article. Though there is hopeful discovery, it is far too early to jump to conclusions without much more research being done. As the research stands, I would not change or alter recommendations for aspirin. There is not enough conclusive evidence for the mechanism of aspirin’s’ effect on gastric cancers. Although there are studies that show aspirin has a positive effect on gastric cancers, more definitive research could also be done in that area as well. Another factor to consider is the risks involved when recommending aspirin. Even if more conclusive data were found, widening the use of aspirin would need to be weighed against its side effects. Aspirin could cause significant bleeding problems in the GI tract, as well as liver and kidney impairment. Without significant data to prove the benefits of aspirin in gastric cancers, recommending aspirin for this therapeutic use is not worth the risks involved.
Do you think this new study has a promising direction of discovery in light of the past research that has been done in this area? What could be the role of aspirin were there more conclusive findings presented in future research and would you change your recommendations based on more conclusive data?
 Rothwell, P; Fowkes, F; Belch, J; Ogawa, H; Warlow, C; Meade, T. Effect of daily aspirin on long-term risk of death due to cancer: analysis of individual data from randomized trials. The Lancet [serial online]. January 2011;377:(9759)31-41. Available from google scholar with Full Text, Ipswich, MA. Accessed October 9, 2013.
 Akre, K; Ekstorm, A; Signorello, L; Hansson, L; Nyren, O. Aspirin and risk for gastric caner: a population based case-control study in Sweden. British Journal of Cancer [serial online]. April 2001;84(7):965-968. Available from google scholar with Full Text, Ipswich, MA. Accessed October 9, 2013.
 Sivarason, N;Smith, G. Role of Aspirin in chemoprevention of esophageal adenocarcinoma: A meta-analysis. Jounral of Digestive Diseases [serial online]. May 2013; 12(5):22-230. Available from Academic Search Complete with Full Text, Ipswich, MA. Accessed October 10, 2013.
 Scientists Explore How Aspirin May Guard Against Cancer. US News Health. June 20 2013.http://health.usnews.com/health-news/news/articles/2013/06/20/scientists-explore-how-aspirin-may-guard-against-cancer. Accessed October 3, 2013.
 Din, F; Dunlop, M; Stark, L; Evidence for colorectal cancer call specificity of aspirin effects on NFkB signaling and apoptosis. British Journal of Cancer [serial online]. July 2004;91(2):381-388. Available from Academic Search Complete with Full Text, Ipswich, MA. Accessed October 9, 2013.
 Rushchoff, J; Wallinger, Dietmaier, W; Bocker, T; Brockhoff, F; Rishel, R. Aspirin suppresses the mutator phenotype associated with hereditary nonpolyposis colorectal cancer by genetic selection. National Academy of Sciences of the United States of America [serial online]. May 1998;95(19):11301-11306. Available from Academic Search Complete with Full Text, Ipswich, MA. Accessed October 10, 2013.