Men with prostate cancer who take anticoagulants like aspirin in addition to radiation therapy or surgery may be able to cut their risk of dying of the disease by more than half, according to a large study presented on November 3, 2010, at the 52nd Annual Meeting of the American Society for Radiation Oncology (ASTRO) in San Diego. The study involved more than 5,000 men with localized cancer whose disease had not spread beyond the prostate gland.

"Evidence has shown that anticoagulants may interfere with cancer growth and spread," Kevin Choe, M.D., Ph.D., lead author of the study and a radiation oncologist at University of Texas Southwestern Medical School in Dallas, said. "If the major effect of anticoagulants is preventing metastasis, this may be why previous clinical trials with anticoagulation medications produced mixed results, since most patients in these trials already had metastasis. If the cancer has already metastasized, then anticoagulants may not be as beneficial."

Researchers evaluated data from the Cancer of the Prostate Strategic Urological Research Endeavor (CaPSURE) database to investigate the effect of anticoagulation medications (aspirin, warfarin, clopidogrel and/or enoxaparin) on the risk of dying from prostate cancer among men whose cancer has not metastasized.

The study involved 5,275 men with localized prostate cancer who were treated with surgery or radiation, two of the most common treatment modalities for prostate cancer. Of these patients, 1,982 were taking anticoagulants. Patients were classified as having high-, intermediate- or low-risk disease.

Results of the study show that the use of anticoagulants among prostate cancer patients treated with either surgery or radiation reduced the risk of dying from the disease from 10 percent to 4 percent at 10 years. The risk of developing bone metastasis was also reduced. In addition, findings reveal that the benefit appeared even greater among patients diagnosed with high-risk prostate cancer.

The study also found that the benefit was most prominent with aspirin, compared to other anticoagulants.

Choe said, "Findings from this study are promising, however, further studies are necessary before the addition of aspirin to prostate cancer therapy becomes standard treatment."