LOS ANGELES, Nov. 1 (UPI) -- Prostate cancer patients cut their risk of dying in half when they receive radiation seed implants, compared to watchful waiting, a U.S. study found.

Watchful waiting, or active surveillance, is an option for some prostate cancer patients especially among older men. Doctors monitor the cancer through frequent tests to see if the tumor causes symptoms or appears to be growing, because most prostate cancers grow very slowly.

Radiation seed implants, or brachytherapy, involves placing small radioactive seeds into the prostate to kill the cancer cells while the man is sedated.

Lead author Dr. Ester H. Zhou, an epidemiologist at the Case Western University School of Medicine in Cleveland, said this is the first time that a population-based cohort study has compared brachytherapy to watchful waiting/active surveillance in the treatment of localized prostate cancer.

"We were pleasantly surprised to find that patients who had brachytherapy in conjunction with external beam radiation therapy and/or androgen deprivation therapy had much better survival than those patients who didn’t receive active treatment, and that it was shown to be just as effective as radical prostatectomy in lengthening the lives of prostate cancer patients," Zhou said in a statement.

The findings were presented at the American Society for Therapeutic Radiology and Oncology’s 49th annual meeting in Los Angeles.