By Pat Anson, Editor

Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) have long been thought to reduce the risk of some cancers. But a surprising new study suggests that regular use of the pain relievers may actually raise the risk of dying for women with endometrial cancer.

Researchers at Ohio State University studied over 4,300 women with endometrial cancer, 550 of whom died during the five-year study. Those who used NSAIDs regularly and had Type 1 endometrial cancer had a 66 percent higher risk of death.

The research findings are published in the Journal of the National Cancer Institute.

"This study identifies a clear association that merits additional research to help us fully understand the biologic mechanisms behind this phenomenon. Our finding was surprising because it goes against previous studies that suggest NSAIDs can be used to reduce inflammation and reduce the risk of developing or dying from certain cancers," said co-author Theodore Brasky, PhD, a cancer epidemiologist at The Ohio State University Comprehensive Cancer Center.

Over 60,000 women are diagnosed with endometrial cancer in the U.S. annually, making it the fourth most common cancer in women and the sixth leading cause of cancer death.

Endometrial cancer begins in the lining of the uterus and grows outward to surrounding organs. Type 1 tumors are less aggressive and are typically confined to the uterus, while Type 2 tumors tend to be aggressive and are at greater risk of spreading.

In the OSU study, the risk of dying was statistically significant in women who reported past or current NSAID use, but it was strongest among patients who used NSAIDs for more than 10 years and had ceased using them prior to their cancer diagnosis.

Interestingly, the use of NSAIDs was not associated with mortality from more aggressive Type 2 cancers.

"These results are intriguing and worthy of further investigation," said co-author David Cohn, MD, director of the gynecologic oncology division at the OSU cancer center. “While these data are interesting, there is not yet enough data to make a public recommendation for or against taking NSAIDS to reduce the risk of cancer-related death."

Aspirin, ibuprofen and other NSAIDs are believed to lower the risk of some cancers by reducing inflammation, which slows the development of blood vessels that support the growth of cancer tumors. Inhibition of inflammation may have the opposite effect in endometrial cancer, but the reasons why are unclear.

Previous studies have shown that NSAIDs have a preventive effect on colorectal cancer and several other cancer types.

“Observational evidence of a chemopreventive effect of aspirin and other NSAIDs has been reported for esophageal, gastric, lung, breast, prostate, and colorectal cancer. Most of these cancers develop after age 60 years,”  researchers at the University of California Irvine reported in The Lancet.

“Given the apparent delay in the chemopreventive effect of NSAIDs (about 10 years), optimum treatment might start at age 40–50 years. Most individuals who develop premalignant lesions do so in their 50s and 60s, several years before the appearance of cancer, so this age range might be the best time for cancer prevention.”

Low-dose aspirin is also believed to have cardiovascular benefits. For that reason, the OSU researchers recommend that women keep taking the pain relievers.  

"It is important to remember that endometrial cancer patients are far more likely to die of cardiovascular disease than their cancer so women who take NSAIDs to reduce their risk of heart attack -- under the guidance of their physicians -- should continue doing so,” said Cohn.