CHICAGO – Doctors are reporting a key advance in treating men with cancer that has started to spread beyond the prostate: Survival is significantly better if radiation is added to standard hormone treatments.

Results of the study were given Sunday at a cancer conference. The drug is being reviewed by the federal Food and Drug Administration.

The prostate study has the potential to change care right away. About 20 percent of the nearly 200,000 men diagnosed with the disease each year in the United States are like those in the study — with cancer that has spread to the area around the prostate.

“It is this group of patients in whom many of the deaths from prostate cancer occur,” because the condition is usually incurable, said study leader Dr. Padraig Warde, a radiation expert from the University of Toronto’s Princess Margaret Hospital.

These men are treated with drugs that block testosterone, a hormone that helps prostate cancer grow. Only about half also get radiation because of concerns about urinary problems it can cause. Even though these treatments have been used for decades, few studies have been done to establish their value alone or in combination.

The new study assigned 1,200 men to get hormones plus radiation or hormones alone. After seven years, 74 percent of men receiving both treatments were alive versus 66 percent of the others. Those on both treatments lived an average of six months longer than those given just hormones.

The study was sponsored by the National Cancer Institute of Canada.