Aspirin and Cancer

Aspirin, a common over-the-counter medication, has shown promising potential in reducing the risk of certain types of cancer, particularly colorectal cancer (CRC). Research indicates that regular use of low-dose aspirin may have significant benefits in cancer prevention and treatment.

Colorectal Cancer

The most consistent and robust evidence for aspirin's anti-cancer effects is in relation to colorectal cancer:

  • Studies show that taking a daily low-dose aspirin (81 mg) could reduce colon and rectal cancer risks by as much as 50%[1].

  • A meta-analysis of cohort studies and randomized controlled trials (RCTs) found that regular aspirin use reduced the risk of CRC (RR=0.85, 95%CI: 0.78-0.92)[2].

  • Long-term aspirin use was associated with a reduced risk of precancerous colorectal polyps[1].

Other Cancers

While the evidence is strongest for CRC, aspirin may also have protective effects against other types of cancer:

  • Gastric cancer: Regular aspirin use was associated with a reduced risk (RR=0.67, 95%CI: 0.52-0.87)[2].

  • Breast cancer: A 16% lower risk was observed with regular low-dose aspirin use, with an even greater reduction (about 20%) for hormone receptor-positive breast cancers[8].

  • Prostate cancer: Some studies suggest a modest risk reduction (RR=0.92, 95%CI: 0.86-0.98)[2].

However, the evidence for these cancers is less consistent than for CRC, and more research is needed.

Mechanism of Action

Aspirin's potential anti-cancer effects are primarily attributed to its anti-inflammatory properties:

  • It reduces chronic inflammation, which can create an environment where cancer thrives[1].

  • Aspirin blocks the production of enzymes that increase inflammation and assist in cancer cell growth[1].

  • Recent research suggests that aspirin may enhance immunosurveillance against colorectal cancer[4].

Dosage and Duration

The most beneficial regimen appears to be low-dose aspirin (75-81 mg) taken daily over an extended period:

  • Long-term use (6 years or longer) was associated with a 19% decreased risk of colorectal cancer[6].

  • A dose-response relationship has been observed, with longer duration of use correlating with greater risk reduction[8].

Risks and Considerations

While aspirin shows promise in cancer prevention, it's not without risks:

  • The primary concern is an increased risk of internal bleeding, especially gastrointestinal bleeding[1].

  • Older adults, those with a history of ulcers, or those taking anticoagulant drugs may be at higher risk of bleeding complications[1].

Current Recommendations

The U.S. Preventive Services Task Force (USPSTF) has recommended low-dose aspirin for the prevention of colorectal cancer in certain individuals, alongside its cardiovascular benefits[6]. However, the decision to start an aspirin regimen should be made in consultation with a healthcare provider, weighing individual risks and benefits.

In conclusion, while aspirin shows significant promise in cancer prevention, particularly for colorectal cancer, it's crucial to consult with a healthcare professional before starting any aspirin regimen. The potential benefits must be carefully balanced against the risks for each individual.

Citations:

[1] https://www.mdanderson.org/publications/focused-on-health/low-dose-aspirin-cancer-prevention.h20-1589046.html

[2] https://pmc.ncbi.nlm.nih.gov/articles/PMC8279749/

[3] https://www.cancer.org/research/acs-research-highlights/colon-and-rectal-cancer-research-highlights/survivorship-colorectal-cancer-studies/regular-use-of-aspirin-may-help-improve-survival-after-a-diagnos.html

[4] https://www.cancercenter.com/community/blog/2024/05/aspirin-and-cancer

[5] https://www.nature.com/articles/s41416-023-02506-5

[6] https://www.cancer.gov/about-cancer/causes-prevention/research/aspirin-cancer-risk

[7] https://www.cardiff.ac.uk/news/view/2782804-aspirin-and-treating-cancer

[8] https://www.health.harvard.edu/blog/aspirin-and-breast-cancer-risk-how-a-wonder-drug-may-become-more-wonderful-2020102321225

Research

Rose, P. W., Watson, E. K., & Jenkins, L. S. 2011. Aspirin for prevention of cancer and cardiovascular disease. Br J Gen Pract, 61(587): 412–415.

Effect of daily aspirin on long-term risk of death due to cancer: analysis of individual patient data from randomised trials Rothwell, Peter M et al. The Lancet, Volume 377, Issue 9759, 31 - 41

Bashir, A. I. J., Kankipati, C. S., Jones, S., Newman, R. M., Safrany, S. T., et al. 2019. A novel mechanism for the anticancer activity of aspirin and salicylates. International Journal of Oncology, 54(4): 1256–1270.

Sandler, R. S., Halabi, S., Baron, J. A., Budinger, S., Paskett, E., et al. 2003. A Randomized Trial of Aspirin to Prevent Colorectal Adenomas in Patients with Previous Colorectal Cancer. The New England Journal of Medicine, 348(10): 883–890.