The Power of Pinpointing

Glioblastoma multiforme may have new radiation treatment options

/ Author:  / Reviewed by: Robert Carlson, M.D

(RxWiki News) There’s a reason it takes a brain surgeon to treat brain cancer. Both the organ and the disease are exceedingly complex. A new finding may offer new ways to treat this aggressive brain cancer.

A recently published study finds that smaller fields of radiation are more effective than larger fields in treating glioblastoma multiforme (GBM), a fast-growing brain cancer. This new technique didn’t affect rate of cancer return.

It was shown to leave more healthy brain tissue untouched. In turn, patients in the study were found to think and feel better. As a result, this approach may improve patients’ quality of life, the researchers believe.

Unfortunately, the technique did not affect how long a patient lived (overall survival).

"Research your cancer therapy."

These are the findings of researchers at the Wake Forest Baptist Medical Center. They examined the records of 161 patients treated for glioblastoma multiforme at their facility over a 10-year period – 2000 -2010. The lead investigator was Assistant Professor of Radiation Oncology, Michael D. Chan, MD.

"For patients with glioblastoma, we now know we can safely and effectively treat them with smaller radiation fields to spare the rest of their normal brain, Dr. Chan said in a statement. ”That's important because it lessens the symptoms from radiation toxicity like tiredness and nausea.”

The patients were treated with varying doses (60 Gy volume and 46 Gy volume) and fields of radiation that ranged from 5- to 20-mm CTV (clinical target value – or area of radiation focus). Some patients also took Temodar (temozolmide), a drug used to treat brain tumors, and others received what’s called IMRT - intensity-modulated radiotherapy.

Researchers were looking for rates of failure based on CTV, use of Temodar and IMRT.

They found that when a lower dose of radiation was used, rates of failure were lowest (48 percent) among patients who received 5-mm CTV compared to 66 percent of patients who got 20-mm CTV. People who were taking Temodar and the higher dose radiation had an 80 percent failure rate. And there was no statistical difference in failure rates among those who received IMRT.

Radiation applied to healthy brain tissue can affect a person’s overall cognition — thinking, reasoning, memory, etc. Using radiation in a smaller area, the researchers found, helped to preserve the patients’ cognition.

Using more pinpointed radiation did not affect the rate of tumor return, however, the method did not extend patients' lives.

dailyRx discussed this study with Keith L. Black, MD, chair and professor of Cedars-Sinai’s Department of Neurosurgery, director of the Cochran Brain Tumor Center and director of the Maxine Dunitz Neurosurgical Institute and the Ruth and Lawrence Harvey Chair in Neuroscience.

“Although it has been recognized for some time that most tumors recur within 2 cm of the resection margin [area around where tumor was surgically removed], it is also known that tumor cell migration is likely throughout the brain. Therefore, extending the radiation margin size may not have the impact one would speculate. These data should help radiation oncologists in their planning of radiation treatments for GBM,” Dr. Black told dailyRx News.

The researchers acknowledged study limitations, including not knowing the exact impact of chemotherapy agents and unknown molecular data.  Dr. Chan nonetheless concluded, “This could potentially be practice changing."

The study was published in the current issue of the American Journal of Clinical Oncology. No financial details were reported.

Reviewed by: 
Review Date: 
January 12, 2013
Last Updated:
January 14, 2013