Brain cancer patients lose some cognitive function after whole-brain radiation treatments, according to a study published online and ahead-of-publication today in The Lancet.

Researchers at the University of Texas MD Anderson Cancer Center in Houston, Texas found that patients getting the full-brain treatment were about twice as likely to undergo learning and memory decline as patients who received the more precise stereotactic radiosurgery.

Unlike whole-brain therapy, which bathes the entire brain in radiation, radiosurgery delivers concentrated doses more precisely to the affected tissue.
In the study, the researchers looked at 58 patients who were diagnosed with one to three brain metastases. About half of the subjects were randomly assigned to a group that just received radiosurgery, while the other half got radiosurgery plus immediate follow up with whole-brain treatment.

All patients were tested four months after their therapies on the revised Hopkins Verbal Learning Test, which measures neurocognitive ability. Results suggest that 52 percent of patients with the whole-brain treatment experienced a significant decline in cognitive function, compared with 24 percent of patients who had only radiosurgery.

The study was stopped early for ethical reasons, as the monitoring committee concluded there was a 96 percent probability that the whole-brain treatment was actually ruining cognitive function.

"Stopping the study early weakened the statistical power for other neurocognitive domains which were secondary endpoints," Eric Chang, M.D., lead author of the study and an oncologist at MD Anderson, tells DOTmed News by email, but not for the primary endpoint of learning and memory.

Cancer Impact

Whole-brain treatment is routinely recommended because it's believed to be better at disease management. And in fact, in the study patients who had whole-brain treatment were more likely to be free from cancer in the central nervous system when checked up on a year later: 73 percent of those with whole-brain therapy were CNS-cancer-free, against the only 27 percent of those who just had radiosurgery.

However, more of the patients with whole-brain treatment died -- a finding that was statistically significant, according to Dr. Chang.

Dr. Chang believes that improved, earlier delivery of chemotherapy -- with additional treatment cycles -- might have contributed to the better survival rates of those who only got radiosurgery.

"The treatment of brain metastases is highly controversial, and has camps on both sides of the argument," Dr. Chang admits. "Those who argue for whole-brain irradiation feel that disease control is the most important goal. However our study shows that these higher recurrences with radiosurgery alone can be managed effectively and also result in improved preservation of learning and memory."

Dr. Chang is planning a follow up study comparing radiosurgery and whole-brain treatment when fighting four or more metastases.

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