By Ed Edelson
TUESDAY, Sept. 23 (HealthDay News) -- The common practice of adding whole brain radiation to more focused radiation treatment for cancers that have spread to the brain not only caused greater learning and memory problems, but also was associated with a shorter survival time in a controlled study.
The survival time data should be approached with caution, because the primary purpose of the study was to help settle a debate about the effects of whole brain radiation on mental function, said study author Dr. Eric L. Chang, an associate professor of radiation oncology at M. D. Anderson Cancer Center in Houston. He presented the results Sept. 22 at the American Society for Therapeutic Radiology and Oncology annual meeting, in Boston.
But, he said, "this report will stimulate a lot of comment because of results we did not expect."
Opinions about the best treatment for cancers that start somewhere in the body and spread to the brain are divided, with some physicians using only stereotactic radiosurgery, which pinpoints radiation directly at the brain cancer colonies, and others adding whole brain radiation, Chang said.
"No one has been able to show that one treatment is better," he said. "It is up to patient preference, physician preference, the philosophy of the institution and what people have been told by their medical oncologists."
The study compared results of treatment for 58 patients with one or more brain metastases --who got either sterotactic radiosurgery alone or accompanied by whole brain radiation.
The study was halted after interim results showed that patients who received both therapies had a 49 percent decline in learning and memory function at four months, compared to those who had stereotactic radiosurgery alone. Their mental function decreased by an average of 23 percent.
Survival time for those getting the single treatment was 15.2 months, compared to 5.6 months for those getting the combined therapy, Chang said.
"The expectation was that the two arms would have similar survival," he said. "We were surprised by that result. Previous studies said there was not a difference in survival time."
Because of the trial results, "personally, I am now very much inclined to offer radiosurgery alone," Chang said.
"We haven't widely shared these results at all," he said, adding that, "I believe this study definitely sheds light on the subject and may establish a new standard of care for this condition."
But the study is unlikely to have a major effect on medical practice for several reasons, said Dr. Minesh Mehta, a professor of human oncology at the University of Wisconsin.
For one thing, "the field already is divided into those who believe in whole brain radiation and those who don't," Mehta said. And those who doubt will note that the study included a small number of patients and took six years to complete, he noted.
The small number could indicate that participants were carefully selected, Mehta said. "The fact that it took so long to accrue the patients in this trial makes you wonder what biases in selection might have skewed the trial," he said.
And the shorter survival time for those who got whole brain radiation "implies that a poorer category of patients were randomized to whole brain radiation," Mehta said.
Another study expected to be reported Sept. 24 at the meeting found unsurprisingly that long-term survivors of adult cancers often have psychological stress severe enough to cause problems in social, work or school situations.
The report came from Harvard Medical School, where researchers used data on 4,712 cancer survivors from a national health study. The average age when cancer was diagnosed was 47, and the survivors were interviewed 15 years later. They were twice as likely to report psychological stress as Americans never diagnosed with cancer, the researchers reported.
Since there are an estimated 12 million American adults who have survived cancer, the finding should "encourage routine psychological screening of these survivors," said a statement by Dr. Karen Hoffman, the Harvard radiation oncologist who was expected to deliver the report.
Learn about radiation treatment of cancer from the American Society for Therapeutic Radiology and Oncology.