Directly to the brain
When cancer spreads to the brain from its original site, such as the lung or breast, it becomes extremely difficult to treat. The organ’s natural barriers tend to block chemotherapy from entering, so that cancer cells survive in the brain even as they are killed off elsewhere.
A possible weapon against this form of the disease, known as metastatic brain cancer, is a therapy currently used for primary brain cancer (in which the tumor originates in the brain).
The treatment, a biodegradable disk containing a strong chemotherapeutic drug, was FDA-approved for primary brain cancer in 1996. Called a GLIADEL wafer, it was the first significant treatment advance in about 20 years and has since helped many patients with primary brain cancer live longer than had been previously possible.
Studies leading to the approval of the device included research by Dr. Henry Brem of Johns Hopkins University. Now his brother, Dr. Steven Brem, is helping to pioneer use of the wafer for metastatic brain cancer.
“Ten years ago, brain metastasis was a pretty gloomy area of medicine,” says Steven Brem, of the H. Lee Moffit Cancer Center in Tampa, Fla. “Once cancer traveled to the brain, many oncologists would despair because they knew there weren’t many good treatments.”
Research on the wafer is ongoing. But in a study of 29 metastatic brain cancer patients who received the GLIADEL wafer after surgery to remove the tumor, none had cancer return in the brain. Typically, there is a 10% chance of recurrence after a metastatic brain tumor is removed.
“When these tumors go to the brain, they don’t usually spread. But they leave a microscopic film that is invisible to the surgeon,” says Brem. Those remaining cells allow the tumor to grow back.
The GLIADEL wafer is placed in the spot where the tumor is removed and delivers chemotherapy to the surrounding tissue for three weeks. The actual wafer is made of a biodegradable polymer that dissolves in about a year.
“The beauty of this is that it does not cause systemic toxicity: Hair doesn’t fall out; you don’t get anemia; you don’t get sick. So patients welcome that,” Brem says, who reported on the study at a meeting of American Assn. of Neurological Surgeons earlier this year.
The half-inch disk can’t be used in all areas of the brain, such as those that affect speech or movement, however, because implanting the device there could impair functions. And patients usually receive medication to prevent seizures, which the wafer can cause. Infection can result from the surgery, Brem adds.
The therapy doesn’t work on the original cancer site. Some patients in the study died because their cancer recurred at the original site.
Still, the treatment is seen as a step forward in an area where options are few. More doctors are expressing interest in trying the therapy, Brem says. “It’s not a cure for brain cancer. It’s additional help. But we’re delighted with the results.”
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An organ that is susceptible
Cancers that spread to the brain from other areas of the body are about 10 times more common than tumors that originate in the brain.
Each year, about 150,000 people in the United States are found to have brain metastases. That number is rising, doctors believe, because treatments for primary cancers are improving and patients are surviving these diseases longer. Older cancer patients are more susceptible to brain metastasis.
Cancers of the lung, breast, colon, kidneys and skin (malignant melanoma) are the most common origins of metastatic brain cancer. Cancer cells spread from these sites to the brain through blood and lymph vessels.
