Will An Aspirin-A-Day Keep Cancer Away?

Aspirin is known to decrease the risk of heart attack when taken regularly.  But did you know that low doses of aspirin have been shown to decrease the risk of cancer also?  When aspirin was taken-daily over several years, recent results point to a decreased risk of various cancers, as well as metastasis of cancers. 

What the research says:

Over the past decades, several studies [4, 5] have demonstrated that aspirin is effective in the prevention of cardiovascular disease for certain populations of people.  Recently, that research has been re-examined to see if there is a link between aspirin and cancers.  Researchers at the University of Oxford in the UK and the American Cancer Society in Georgia recently published results demonstrating reductions in various cancers [1,2] with long-term aspirin treatment.  More specifically, long-term aspirin use resulted in 30% less colorectal cancer, and approximately 20% lower prostate cancer when used daily for more than 5 years[7].  In a similar study, aspirin use was also found to decrease the incidences of colorectal, esophageal, gastric, biliary, and breast cancer in another study [2,9]. Regular use of aspirin was associated with a reduced proportion of cancers metastasizing to distant locations in the body [2]. 

You’re probably asking yourself why aspirin would modulate cancer risk.  Well, it appears that aspirin’s antiinflammatory properties may help alleviate diseases that are linked to chronic inflammation.  What’s chronic inflammation? Chronic inflammation occurs when the body’s normal inflammatory response is no longer transient but persists and starts damaging the body itself.  Chronic inflammation has been linked to various diseases, including various forms of cancer, heart disease and rhuematoid arthritis [10]. 

What exactly is the relationship between aspirin and heart disease?

Over the past decades, several studies [4, 5] have demonstrated that aspirin is effective in the prevention of cardiovascular disease for certain populations of people (notably men and women up to 80 years old at risk for cardiovascular disease) [3].  This happens because aspirin functions as an anti-thromus agent, which means it prevents platelets from binding together to form clots.  By avoiding the formation of clots, they avoid the likelihood of strokes and heart attacks.  However, this also means that there is an increased incidence of bleeding-related illnesses, such as gastrointestinal hemmoraghing and hemorraghic stroke, when taking aspirin [6].   So it’s important to weigh the benefits versus the risks when engaging in long-term aspirin treatments.  Studies seems to agree, though, that those at risk of cardiovascular disease benefit from a daily-dose of aspirin [6]. 

How much aspirin and how often?

The amount of aspirin needed is open for debate.  When cardiovascular events were analyzed, benefits of aspirin treatment were equivalent for either medium doses (70-325 mg/day) or adult-doses (>325 mg/day).  Ultimately, they concluded long term use with doses as low as 75 mg daily were effective for decreasing the risk of cardiovascular disease [8]. 

When focusing on cancer risk, studies have shown that taking adult-doses of aspirin (more than 300 mg/day) for at least 5 years was required [7,9].   That would equate to medium or adult doses of aspirin daily.

References:

1.     Daily Aspirin Use and Cancer Mortality in a Large US Cohort.  Jacobs EJ, Newton CC, Gapstur SM, Thun MJ. J Natl Cancer Inst. 2012 Aug 1;104(16):1208-17. Epub 2012 Aug 10.

2.     Effects of regular aspirin on long-term cancer incidence and metastasis: a systematic comparison of evidence from observational studies versus randomised trials.  Algra AM, Rothwell PM.  Lancet Oncol. 2012 May;13(5):518-27. Epub 2012 Mar 21.

3.     Effects of combined aspirin and clopidogrel therapy on cardiovascular outcomes: a systematic review and meta-analysis.  Zhou YH, Wei X, Lu J, Ye XF, Wu MJ, Xu JF, Qin YY, He J. PLoS One. 2012;7(2):e31642. Epub 2012 Feb 13.

4.     Aspirin for the prevention of cardiovascular events in patients without clinical cardiovascular disease: a meta-analysis of randomized trials.  Berger JS, Lala A, Krantz MJ, Baker GS, Hiatt WR.  Am Heart J. 2011 Jul;162(1):115-24.e2. Review.

5.     Aspirin for primary prevention: yes or no?  Selak V, Elley CR, Wells S, Rodgers A, Sharpe N.  J Prim Health Care. 2010 Jun;2(2):92-9.

6.     The aspirin controversy in primary prevention. Raju NC, Eikelboom JW. Curr Opin Cardiol. 2012 Sep;27(5):499-507.

7.     A large cohort study of long-term daily use of adult-strength aspirin and cancer incidence.  Jacobs EJ, Thun MJ, Bain EB, Rodriguez C, Henley SJ, Calle EE. J Natl Cancer Inst. 2007 Apr 18;99(8):608-15.

8.     Collaborative overview of randomised trials of antiplatelet therapy--I: Prevention of death, myocardial infarction, and stroke by prolonged antiplatelet therapy in various categories of patients. Antiplatelet Trialists' Collaboration.  BMJ. 1994 Jan 8;308(6921):81-106. Erratum in: BMJ 1994 Jun 11;308(6943):1540.

9.     Effect of aspirin on long-term risk of colorectal cancer: consistent evidence from randomised and observational studies.  Flossmann E, Rothwell PM; British Doctors Aspirin Trial and the UK-TIA Aspirin Trial.  Lancet. 2007 May 12;369(9573):1603-13. Review

10.   Multifaceted link between cancer and inflammation.  Sethi G, Shanmugam MK, Ramachandran L, Kumar AP, Tergaonkar V.  Biosci Rep. 2012 Feb;32(1):1-15. Review.