Whole-Brain Radiation Affects Learning, Memory
CancerWise - December 2008
When patients with cancer that has metastasized (spread) to the brain are treated with whole-brain radiation therapy (WBRT), their risk of developing learning and memory problems increases dramatically.
A Phase III study at M. D. Anderson showed that pairing WBRT with stereotactic radiosurgery (SRS), a type of targeted radiation therapy, doubles the risk of learning and memory problems compared to treatment with SRS alone.
Results of the study were presented at the annual meeting of the American Society for Therapeutic Radiology and Oncology.
Significance of results
This year, about 170,000 cancer patients will experience metastases to the brain from common primary cancers such as breast, colorectal, kidney and lung, according to the American Cancer Society.
"Determining how to achieve the best outcomes with the smallest cost to the quality of life is a treatment decision every radiation oncologist faces," says Eric Chang, M.D., associate professor in the Division of Radiation Oncology at M. D. Anderson.
"While WBRT and SRS are in practice and equally acceptable, data from this trial suggest that oncologists should offer SRS alone as the upfront, initial therapy for patients with up to three brain metastases,” he says.
SRS has become widely used over the past decade as an initial treatment for cancers that have spread to the brain. It is often combined with WBRT.
The study builds on previous research by senior author Christina Meyers, Ph.D., chief of the Section of Neuropsychology in the Department of Neuro-Oncology at M. D. Anderson, which examined memory and learning problems in patients with brain metastases treated with WBRT.
This seven-year study observed 58 patients with one to three newly diagnosed brain metastases.
They were assigned randomly to receive either:
- SRS followed by WBRT
- SRS alone
Using standardized tests, researchers measured participants' learning and memory function before and after treatment.
Approximately four months after treatment, learning and memory function declined in:
- 49% of patients who received SRS plus WBRT
- 23% of patients who received SRS alone
An independent data monitoring committee stopped the study after early results showed most patients (96.4%) performed better when treated with SRS alone.
"The risks of learning dysfunction outweigh the benefits of freedom from progression and tip the scales in favor of using SRS alone,” Chang says.
"Unlike past studies comparing the two treatment strategies that did not use sensitive cognitive tests or closely follow patients after being treated with SRS alone, radiation oncologists in this trial were able to identify new lesions early and treat them," Meyers says. "We believe doctors and patients alike will favor this method instead of SRS plus WBRT as an initial treatment."
Based on these results, future research will study patients with more than three brain metastases being treated with SRS alone and compare them to patients treated with WBRT alone, the current standard of care.