CHICAGO, June 30 (Xinhua) -- The situation of limited treatment options for men with non-metastatic castrate-resistant prostate cancer and a quickly rising prostate-specific antigen (PSA) level may be broken.

A study by researchers at Northwestern University (NU) Medicine shows that a drug currently used to treat men with metastatic, advanced prostate cancer significantly lowered the risk of metastasis or death when used in the patients.

The trial included about 1,400 men with PSA levels that had doubled in 10 months or less and were continuing androgen-deprivation therapy. For every three patients in the trial, two got the drug and one got the placebo.

The median duration of the trial regimen was 18.4 months in the enzalutamide group and 11.1 months in the placebo group. The median metastasis-free survival was 36.6 months in the enzalutamide group, as against 14.7 months in the placebo group. When the trial was over, the men on the placebo received the real drug.

Men who took the drug, enzalutamide, had a 71 percent lower risk of metastasis or death than those who took the placebo over the three-year duration of the trial. They also had delayed cancer re-appearance of almost two years compared to those taking a placebo.

These include a greater decline in PSA and less need for additional anticancer treatments without a negative impact on quality of life.

"Our goal was to see if we could delay the re-appearance of cancer with the hope it will lead to prolonged life," said lead study author Maha Hussain, professor of medicine at Northwestern University (NU) Feinberg School of Medicine. "We have to do more follow-up over time to see if long-term survival is impacted, but there are early positive trends."

Prostate cancer feeds on testosterone. The drug, enzalutamide, targets the androgen receptor on the cancer cell that is like a tiny landing pad for male hormones. It closes down the runway and starves the cell of testosterone and other male hormone-like substances. Some cancer cells may die; some may go dormant.

"By treating men earlier when they have less cancer, the drug can be more effective," Hussain said.

The U.S. Food and Drug Administration is reviewing approval of enzalutamide for men with non-metastatic castrate-resistant prostate cancer, Hussain said.

The study was published June 28 in the New England Journal of Medicine.