Aspirin reduces risk of colorectal cancer incidence, mortality

December 1, 2010

Aspirin taken for several years and at doses ?75 mg a day was found to result in both a reduced 20-year risk of colorectal cancer incidence and mortality, according to an analysis published ahead-of-print on the Lancet website.

Key Points

Aspirin taken for several years and at doses ≥75 mg a day was found to result in both a reduced 20-year risk of colorectal cancer incidence and mortality, according to an analysis published ahead-of-print on the Lancet website.

The authors of this study lead by Peter M. Rothwell, MD, Department of Clinical Neurology, University of Oxford, Oxford, UK, emphasized, "Benefit was greatest for cancers of the proximal colon, which are not otherwise prevented effectively by screening with sigmoidoscopy or colonoscopy."

They conducted an independent patient data meta-analysis that followed 14,033 patients for about 20 years of follow-up as part of 5 pooled randomized trials assessing the effect of aspirin on colorectal cancer incidence and mortality. Their analysis focused, not only on overall incidence and mortality rates, but also on the effect of the site of tumor and aspirin dose and duration of treatment.

The authors stressed, "The 5 trials we studied all predated endoscopic screening for adenomas, which also reduces colorectal cancer incidence and mortality, and might therefore reduce the absolute benefit of aspirin."

They also found the benefit of aspirin increased with longer durations of treatment, with participants receiving aspirin for at least 5 years exhibiting a reduced risk of proximal colon incidence and related mortality and also a reduced risk of rectal cancer incidence and mortality. Doses of aspirin ≥75 mg/d showed no additional benefit, but doses of 30 mg/d appeared less effective.

"This . . . could incite clinicians to turn to primary prevention of colorectal cancer by aspirin, at least in high-risk populations," said Robert Benamouzig, MD, and Bernard Uzzan, MD, the Departments of Gastroenterology and Pharmacology at Avicenne Hospital, France.

SOURCES

Rothwell PM, Wilson M, Elwin CE, et al. Long-term effect of aspirin on colorectal cancer incidence and mortality: 20-year follow-up of 5 randomised trials. Lancet. 2010;Oct 21. [Epub ahead of print]. Available at: http://www.lancet.com/journals/lancet/article/PIIS0140-6736%2810%2961543-7/fulltext. Accessed November 20, 2010.

Benamouzig R, Uzzan B. Aspirin to prevent colorectal cancer: time to act? Lancet. 2010;Oct 21. [Epub ahead of print]. Available at: http://www.lancet.com/journals/lancet/article/PIIS0140-6736%2810%2961509-7/fulltext. Accessed November 20, 2010.

U.S. Cancer Statistics Working Group. United States Cancer Statistics: 1999–2006 Incidence and Mortality Web-based Report. Atlanta (GA): Department of Health and Human Services, Centers for Disease Control and Prevention, and National Cancer Institute; 2010. Available at: http://www.cdc.gov/uscs/. Accessed November 20, 2010.