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TUESDAY, June 17 (HealthDay News) -- Countering common medical theory, a new study finds that radiation therapy may save the lives of many men whose prostate cancer recurs aggressively after surgery.

"We show that even men with aggressive disease that recurs after surgery seem to benefit from salvage radiotherapy," said lead researcher Bruce J. Trock, associate professor of urology at Johns Hopkins University in Baltimore. "In the past, surgeons would have said that the tumor had spread to other parts of the body and that salvage radiotherapy was not appropriate," he noted.

The belief was that radiation therapy would not help, because it was aimed only at the original tumor site.

But the study of 635 men who had surgery for prostate cancer and then showed signs of recurrence found that the death rate for those who got radiation therapy was half that of men who didn't.

The study, published in the June 18 issue of the Journal of the American Medical Association, was relatively small and needs confirmation, Trock said. "But if it is true, it suggests that more men have recurrence at the local site than has been suspected in the past," he said.

The benefit was greatest for those men with aggressive cancers -- patients whose blood levels of prostate-specific antigen (PSA), a marker for disease activity, doubled in less than six months. Among the 126 men in the study with aggressive disease, the death rate was 75 percent lower for those given salvage radiotherapy versus those who didn't get the treatment.

Over a follow-up period averaging six years after recurrence, death rates were 11 percent for those who had salvage therapy alone, 12 percent for those who got radiation plus hormonal therapy, and 22 percent for men who had no salvage radiation therapy.

The study was called "a very important contribution to our further knowledge about salvation radiotherapy after recurrence" by Dr. Michael J. Zelefsky, professor of radiation oncology at Memorial Sloan-Kettering Cancer Center in New York City.

"It makes two very important points," Zelefsky said. "One is that in order to achieve optimal results, you have to give salvation radiotherapy sooner rather than later, before two years have elapsed. After two years, the results are less optimal.

"Second, the surprising thing to come out of the study is about people who have rapid PSA doubling time. Normally, you think of those patients as having more aggressive disease that has spread elsewhere. This suggests otherwise, that even though the doubling time is more rapid, you still get excellent outcomes with radiotherapy."

Cancer specialists might have to start thinking differently about such cases, Zelefsky said. "People usually have a fatalistic approach when it comes to those patients who present with recurrence and a rapid PSA doubling time," he said. "Now, you might be able to cure them."

It is hard to say whether the report will have an immediate impact on medical practice, both Trock and Zelefsky said. "The study needs to be validated in a formal, randomized controlled trial," Zelefsky said.

But such a study might be beyond the capability of an individual cancer center, Trock said. "You would need at least one or more large institutions with large data bases to validate our results," he said.

More information

Facts on the incidence and treatment of prostate cancer are available from the National Cancer Institute.