There is a growing body of evidence that certain pain relievers may have a role in cancer prevention and treatment, especially for colorectal and breast cancer.

While results are mixed, the medical community is investing significant attention and resources to this subject. Researchers are hopeful that someday these drugs may lead to new opportunities in the fight against cancer.

The pain relievers in questions fall into two general categories: NSAIDs (nonsteriodal anti-inflammatory drugs), such as aspirin, ibuprofen (Motrin), and naproxen (Aleve), and selective COX (cycooxygenase) inhibitors, such as Celebrex.

Recently, the American Association for Cancer Research (AACR) reported that aspirin and other NSAIDs might protect against breast cancer and ovarian cancer in postmenopausal women. Regular use of these pain relievers modestly lowered estrogen levels, which scientists believe may reduce cancer risk by suppressing hormones that fuel tumors. Some studies have found that, with regular use, certain COX (regulatory enzymes) inhibitors reduce breast cancer risk as well.

Studies also show that NSAIDs reduce the risk of colorectal cancer when taken at high doses for long periods, and regular aspirin therapy following a colorectal cancer diagnosis seems to lower mortality over the next 12 years.

How They Work
Here's how these pain relievers work and why the cancer community is so interested in them.

Aspirin and other NSAIDs regulate the proliferation, or the rapid and sometimes excessive growth, of cells by suppressing enzymes that lead to the development of prostaglandins through the inhibition of COX. Prostaglandins are a type of fatty acids involved in a variety of physiological functions. Precancerous tissue produces prostaglandins and our body produces them when inflammation is present. COX inhibitors may also have value as a chemo protective agent.

Risks and Side Effects
NSAIDs, however, increase the risk of gastrointestinal bleeding and stomach ulcers with regular use. While these side effects are rare, they are potentially serious. Furthermore, over the long term, NSAIDs may increase individuals' risk for heart attack and stroke.

In evaluating whether pain relievers may be beneficial in the prevention and treatment of cancer, physicians must weigh these risks against the potential benefits. To date, the United States Preventive Services Task Force, an independent advisory panel, does not recommend routine use of pain relievers to prevent colorectal cancer in people with average risk, claiming the harms outweigh the benefits. However, the accumulating data suggests there may be a future role for NSAIDs. Many clinical trials are underway so physicians can learn more.

Boylels, Salynn. "Pain Relievers May Reduce Cancer Risk." American Association of Cancer Research." Web. 24 March 2010.

University of Maryland Medical School. "Colon and rectal cancers - Risk Factors and Prevention." Web.

U.S. Preventive Services Task Force. "Routine aspirin or nonsteroidal anti-inflammatory drugs for the primary prevention of colorectal cancer: U.S. Preventive Services Task Force recommendation statement." Annals of Internal Medicine 146(5) (2007): 361-4. Web.

Cronin-Fenton, Deirdre P., Pedersen, Lars, Lash, Timothy L., Friis, Soren, Baron, John A., and Sørensen, Henrick T. "Prescriptions for Selective Cyclooxygenase-2 Inhibitors, Non-selective Non-steroidal Anti-inflammatory Drugs, and Risk of Breast Cancer in a Population-based Case-control Study. Medscape Medical News. Web. 17 June 2010.

Komaroff, Anthony L. MD. "Aspirin Lengthens Survival in Patients with Nonmetastatic Colorectal Cancer." Medscape Medical News. Web. 16 November 2009.

Agrawal, A., and Fentiman, S. "NSAIDs and Breast Cancer: A Possible Prevention and Treatment Strategy." International Journal of Clinical Practice 62(3) (2008): 444-449. Medscape Medical News. Web. 21 March 2008.

Lanas, Angel, and Ferrandez, Angel. "NSAIDs and the Colon." Current Opinion in Gastroenterology 25(1) (2009): 44-49. Medscape Medical News. Web. 15 April 2009.

Brooks, Megan. "NSAIDs Linked to Lower Mortality After Colorectal Cancer Diagnosis." Cancer 2009. Medscape Medical News. Web.

National Cancer Institute. "NCI-Sponsored Trials of Cyclooxygenase (COX) Inhibitors for Cancer Prevention and Treatment." Web. 17 December 2004.