Thanks to its wide range of medicinal benefits, aspirin is one of the most commonly used medications in the world. There is extensive evidence suggesting benefit from aspirin in preventing cancer growth and metastatic spread. Evidence on biological mechanisms include reductions by aspirin in cancer-related inflammation, abnormal clotting, abnormal blood vessel growth, and enhancement in cellular repair processes.
In a recent review published in Open Biology, researchers discussed the existing evidence on the use of acetylsalicylic acid (aspirin) in cancer treatment. They conducted a literature review to understand how aspirin influences biological mechanisms in cancer and summarized the findings from clinical trials and observational studies involving aspirin in cancer treatment. Lead author Professor Peter Elwood, former Director of the MRC Epidemiology Unit in South Wales and Honorary Professor at Cardiff University tells us more about his and his colleagues’ work.
Please could you tell us a little bit about your article?
Our article is one of a series of reports which examine the case for aspirin as a possible additional treatment of cancer. Another report1 in the series examine the side effects of aspirin and, on the basis that the severity of bleeding attributable to aspirin appears to be less that ‘spontaneous’ bleeds from peptic ulceration and infections with Helicobacter pylori (H. pylori), and there appears to be no valid evidence of fatal bleeding attributable to aspirin.
Aspirin is a seemingly humble drug, what first attracted you to look at its potential beyond pain relief medicine?
In 1974 we reported the first randomised trial of aspirin in the reduction of vascular mortality, and our report went global!2 Twenty-five years later evidence form long-term follow-up studies of early vascular trials showed evidence suggestive of a reduction in cancer incidence and mortality. My research team and I decided to focus research on aspirin as a possible treatment of cancer. Our main strategy was to conduct systematic searches of the literature for studies of aspirin taken by patients with cancer. In three replicate searches over the following five years3-5 we identified 118 observational cohort and case-control studies, and a very small number of randomised trials. Meta-analyses of the observational studies showed a pooled hazard ratio (HR) for cancer deaths of 0.77 (95% CI (o.72, 0.83) in 70 reports based upon 18 different cancers, and an HR of 0.79 (0.74, 0.86) for all-cause deaths in 56 reports.
Were there any surprises while looking at the at the effects of aspirin in relation to the biological mechanisms of cancer?
Yes and no! We expected to see clear relationships between the effects of aspirin upon the biological mechanisms of cancer and the clinical outcomes of a reduction in mortality, a reduction in cancer metastatic spread and the vascular complication of cancer… but we were surprised and delighted at the ‘harmony’ of the relationships between these two sources of evidence – aspirin: biological mechanisms and clinical outcomes!
Where would you like to see research in the field heading?
We believe that the series of studies we have reported – and in particular the evidence on the relative safety of aspirin - have provided evidence that is sufficient to justify the recommendation of aspirin to patients with cancer. We see our task now to be persuading oncologists to examine the evidence.
1. Elwood PC, Morgan G, Galante J, Chia JWK, Dolwani S, Gaziano JM, Kelson M, Lanas A, Longley M, Phillips CJ, Pickering J, Roberts S, Soon SS, Steward W, Morris D, Weightman AL. Systematic review and meta-analysis of randomised trials to ascertain fatal gastrointestinal bleeding events attributable to preventive low-dose aspirin: No evidence of increased risk, PLOS, 2016. http://dx.doi.org/10.1371/journal.pone.0166166.
2. Elwood PC, Cochrane AL, Burr ML, Sweetnam PM, Williams G, Welsby E, Hughes SJ, Renton R. A randomized controlled trial of acetyl Salicylic Acid in the secondary prevention of mortality from myocardial infarction. Br Med J. 1974;1:436-440.
3. Elwood PC, Morgan G, Pickering JE, Galante J, Weightman A, Morris D, Kelson M, Dolwani S. Aspirin in the treatment of cancer: reductions in metastatic spread and in mortality: a systematic review and meta-analysis of published studies. PLOS April 20, 2016.
4. Elwood PC, Pickering JE, Morgan G, Galante J, Weightman AL, Morris D, Longley M, Mason M, Adams R, Dolwani S Chia JWK, Lanas A. Systematic review update of observational studies further supports aspirin role in cancer treatment: time to share evidence and decision-making with patients? 2018. https://doi.org/10.1371/journal.pone.0203957.
5. Elwood PC, Morgan G, Delon C, Protty M, Galante J, Pickering J, Watkins J, Weightman A, Morris D. Aspirin and cancer survival: a systematic review and meta-analyses of 118 observational studies of aspirin and 18 cancers. ecancer 2021;15:1258.
Images and image credits:
Thumbnail image: Peter Elwood, Cardiff University. Credit: Cardiff University
Hero image: Aspirin. Wikimedia Commons CC-BY-SA-4.0