Some studies have shown that blood-thinning medications, such as aspirin, can reduce biochemical failure––cancer recurrence that is detected by a rising prostate-specific antigen (PSA) level––the risk of metastasis and even death in localized prostate cancer. These studies, although very telling, have all emphasized the need for more data. Now, with researchers at Fox Chase Cancer Center having concluded the largest study on this topic, and there is substantial data suggesting that aspirin improves outcomes in prostate cancer patients who have received radiotherapy.
A team led by Mark Buyyounouski, M.D., M.S., a radiation oncologist at Fox Chase, examined a database of over 2000 prostate cancer patients who underwent radiotherapy at Fox Chase between 1989 and 2006 and found that aspirin use lowers the risk of cancer recurrence. The scientists will present their findings on Sunday, May 1 at the 93rd Annual Meeting of the American Radium Society.
The team found that the 761 men who took aspirin at or after the time of radiotherapy were less likely to experience biochemical failure––as indicated by the levels of PSA––than were the 1380 men who didn't take the drug.
After 10-years from completion of treatment, 31% of the men who took aspirin developed recurrence compared with 39% of non-aspirin users (p=0.0005). There was also a 2% improvement in 10-year prostate cancer related survival associated with aspirin use with a trend toward statistical significance (p=0.07). "We know that prostate cancer has a long natural history and 15 years or more may be necessary to detect significant difference in survival," Dr. Buyyounouski explains. "Longer follow-up is needed, but these results warrant further study."
The readily available drug could be a promising supplement to radiotherapy in prostate cancer patients, and its beneficial effects may generalize to other types of cancer, Buyyounouski says. Still, he cautions that "it's a little premature to say that men need to start taking aspirin if they have a history of prostate cancer."
The optimal dose, timing, and duration of aspirin therapy, as well as potential side effects are not well understood, Buyyounouski explains. It's not clear how exactly the aspirin is helping and more research is needed to investigate this. "Its possible aspirin therapy is making the radiation more effective or preventing the cancer from spreading".
"Hopefully, these clinical results will provide feedback to laboratory researchers to try to explain the underlying mechanism so that we can better study the clinical effects in targeted populations," Buyyounouski says.