Aspirin, long used as an analgesic and fever reducer, has more recently come into favor for its influence on vascular health. Now, accumulating evidence is pointing to aspirin's benefit in the prevention and treatment of some forms of cancer. Along with ibuprofen, aspirin is one of the non-steroidal, anti-inflammatory drugs also know as NSAIDs. Aspirin's beneficial role in relationship to cancer is thought to stem primarily from its anti-inflammatory properties, but additional biochemical effects are also involved. Although this drug's precise mechanism of action is not entirely understood, recent research is uncovering how aspirin can help with cancer prevention and treatment.
Research
Colon cancer:
Although aspirin is showing promise as a prevention for many types of cancer, research for its role in preventing colon cancer is the most convincing to date. According to a consensus statement in the May 2009 issue of the Lancet Oncology, "Evidence clearly shows a chemopreventive effect for aspirin and other non-steroidal anti-inflammatory drugs on colorectal cancer and probably other cancer types."
Data from the Aspirin/Folate Polyp Prevention Trial in the October 12, 2009 issue of the Journal of the National Cancer Institute found that aspirin reduced the recurrence of colorectal adenomas, which can be precursors to colorectal cancer. Regular aspirin use resulted in an absolute risk reduction of 6.7 percent for developing adenomas compared to placebo. Additionally, an article in the August 12, 2009 issue of the Journal of the American Medical Association discusses results from the Nurses' Health Study, and the Health Professionals Follow-up Study. Both studies showed that regular aspirin use after diagnosis was associated with a significant reduction in the risk of colorectal cancer death, and in overall mortality.
Breast cancer:
Aspirin offers moderate risk reduction for breast cancer, according to a review of data in the "International Journal of Clinical Practice." The article concludes that NSAIDs may reduce the risk of breast cancer by 20 percent.
Other cancers:
Aspirin may also reduce the risk for several other types of malignancies including bladder, prostate, lung, Hodgkin's lymphoma and gastric cancers, but studies are limited.
Mechanisms
Inflammation is one component in the development of cancer. Aspirin inhibits cyclooxygenase- 2, thereby reducing the synthesis of inflammatory prostaglandins. This COX- 2 inhibition is believed to be aspirin's primary influence in cancer risk reduction. Other proposed mechanisms involved are aspirin's ability to inhibit NF-kappa B, Cytokins, and tumor necrosis factor. Increased synthesis and dysregulation of these biological compounds can promote inflammation. Platelet aggregation is another factor in cancer development and metastasis. Inhibition of platelet aggregation may play a part in aspirin's cancer-fighting properties. In patients with breast cancer, aspirin increases levels of serum nitric oxide, which inhibits growth of breast cancer cells in vitro.
Warnings
Even as evidence emerges for aspirin's potential benefit in cancer prevention, it currently is not recommended as a prophylactic for cancer. Further studies are needed to understand proper dosage and duration of use. Safety issues are a concern, as aspirin carries risk of gastrointestinal bleeding and can interfere with other medications.
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