Men with prostate cancer that comes back after surgery live longer if they undergo radiation afterward and also take drugs to block tumor-feeding male hormones.

The finding, published in The New England Journal of Medicine, is from a long-running study that experts say will help clarify treatment for many patients, The New York Times reports.

One in three prostate cancer survivors have a recurrence after surgery and until now there has not been clear evidence about the best way to stop the disease from killing them. Most are given radiation, but the new study, funded by the National Cancer Institute, showed that among men who also received hormonal treatment, 76.3 percent were still alive after 12 years, compared to 71.3 percent who had radiation alone.

At 12 years, the men who had both treatments were also much less likely to have died from their prostate cancer — 5.8 percent versus 13.4 percent — or to have the cancer spread to other parts of the body — 14.5 percent versus 23 percent.

“This is a big deal,” said Dr. Ian M. Thompson Jr., of the Christus Santa Rosa Health System in San Antonio, who was not part of the study but wrote an editorial accompanying it.

“There are so many things we do in prostate cancer that we don’t know if they make a big difference in survival. This is one of the things where now we can say for sure.”