Prophylactic Aspirin Reduces Cancer Risk

The risk-to-harm balance tips in favour of daily prophylactic aspirin

medwireNews: Research supports the use of daily aspirin in older adults to reduce the risk of cancer and vascular disease, suggests a review published in the Annals of Oncology.

Jack Cuzick, from Queen Mary University of London in the UK, and co-authors reviewed current cardiovascular and cancer data to determine the benefit–harm balance of prophylactic aspirin in the general population.

For men and women aged 50 to 65 years, considered to be at average risk of cancer, taking aspirin for 10 years was estimated to give a respective 9% and 7% relative risk of reduction in the likelihood of malignancy, myocardial infarction or stroke over 15 years.

Some of the authors expressed uncertainty about the strength of evidence for a risk reduction with aspirin in lung, breast and prostate cancers; however, the research indicated a net benefit in favour of aspirin use even when considering only colorectal cancer.

As expected, daily aspirin would also increase the 15-year risk of major bleeding events by a conservative estimate of between 0.21% and 1.05% compared with baseline, depending on age and gender.

Nevertheless, over 20 years, aspirin prophylaxis would translate to a conservative 4% relative reduction in the number of deaths of men and women, the researchers report, with men and older individuals most likely to benefit.

This gives a number needed to treat for 10 years to prevent one major event of between 33 and 127, the team explains.

“The benefits of aspirin are at least equivalent in magnitude to those from statins, and as they mostly relate to cancer, are complimentary to statins”, Jack Cuzick et al comment.

Indirect comparisons found little difference in the prophylactic qualities of low-dose (75–100 mg/day) and standard-dose (300–325 mg/day) aspirin.

The authors therefore suggest that further research is required to determine the optimal dose for individuals in the general population and those at particularly high risk of disease, and to determine at what age patients should discontinue aspirin prophylaxis due to the increasing risk of bleeding with older age.

The researchers note that the study used data from the developed world and that further investigation is necessary to determine the benefits for patients in regions where cancer incidence is lower and Helicobacter pylori infection is more common.

“A 2 × 2 × 2 factorial trial could address all three of these questions—low versus standard dose, 5 versus 10 years duration of use and H. pylori screen-and-treat versus symptom-directed management”, the team concludes.

“However, separate trials could be done if deemed logistically more attractive.”

Reference

Cuzick J, Thorat M, Brown P, et al. Estimates of benefits and harms of prophylactic use of aspirin in the general population. Ann Oncol 2014; First published online 5 August. doi: 10.1093/annonc/mdu225

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