Study: Women who take aspirin daily may reduce risk of ovarian cancer by 20%

Women who take aspirin daily may reduce their risk of ovarian cancer by 20 percent, according to a study by scientists at the National Cancer Institute (NCI), part of the National Institutes of Health. However, further research is needed before clinical recommendations can be made. The study was published Feb. 6, 2014, in the Journal of the National Cancer Institute.

It is estimated that over 20,000 women in the United States will be diagnosed with ovarian cancer in 2014, and more than 14,000 will die from the disease. Early stage ovarian cancer may be successfully treated. However, symptoms associated with this disease can mimic more common conditions, such as digestive and bladder disorders, so for this reason and others, it is often not diagnosed until it has reached advanced stages. Late stage ovarian cancer leaves women with limited treatment options and poor prognoses, making preventive strategies potentially important for controlling this disease.

Chronic or persistent inflammation has been shown to increase the risk of cancer and other diseases. Previous studies have suggested that the anti-inflammatory properties of aspirin and non-aspirin NSAIDs (non-steroidal anti-inflammatory drugs), may reduce cancer risk overall. However, studies examining whether use of these agents may influence ovarian cancer risk have been largely inconclusive. This is the largest study to date to assess the relationship between these drugs and ovarian cancer risk.

Britton Trabert, Ph.D., and Nicolas Wentzensen, M.D., Ph.D., of NCI's Division of Cancer Epidemiology and Genetics, and their colleagues, analyzed data pooled from 12 large epidemiological studies to investigate whether women who used aspirin, non-aspirin NSAIDs, or acetaminophen have a lower risk of ovarian cancer. These 12 studies (nine from the United States) were part of the Ovarian Cancer Association Consortium. The scientists evaluated the benefit of these drugs in nearly 8,000 women with ovarian cancer and close to 12,000 women who did not have the disease.

Among study participants who reported whether or not they used aspirin regularly: 18 percent used aspirin, 24 percent used non-aspirin NSAIDs, and 16 percent used acetaminophen. The researchers determined that participants who reported daily aspirin use had a 20 percent lower risk of ovarian cancer than those who used aspirin less than once per week. For non-aspirin NSAIDs, which include a wide variety of drugs, the picture was less clear: the scientists observed a 10 percent lower ovarian cancer risk among women who used NSAIDs at least once per week compared with those who used NSAIDs less frequently. However, this finding did not fall in a range that was significant statistically. In contrast to the findings for aspirin and NSAIDs, use of acetaminophen, which is not an anti-inflammatory agent, was not associated with reduced ovarian cancer risk.

This study adds to a growing list of malignancies, such as colorectal and other cancers, that appear to be potentially preventable by aspirin usage. "Our study suggests that aspirin regimens, proven to protect against heart attack, may reduce the risk of ovarian cancer as well. However intriguing our results are, they should not influence current clinical practice. Additional studies are needed to explore the delicate balance of risk-benefit for this potential chemopreventive agent, as well as studies to identify the mechanism by which aspirin may reduce ovarian cancer risk," said Trabert.

Adverse side effects of daily aspirin use include upper gastrointestinal bleeding and hemorrhagic stroke. Therefore, a daily aspirin regimen should only be undertaken with a doctor's approval, caution the scientists.