Wafers on the Brain
BRAIN TUMORS ARE ONE of the most frightening forms of cancer as they damage the soft sponge, packed inside the skull, that controls our lives. Symptoms include headaches, seizures and problems with memory, speech and communication. Often treatment can only slow the spread of the tumor — the odds for survival are bleak. "Most people are dead within six months of diagnosis," says Dr. Prem Pillay, a neurosurgeon in private practice in Singapore. But there is a glimmer of hope from a radical new treatment which doubles survival time and may increase the survival rate.
Usually the first step in treatment is surgery to remove as much of the tumor as possible. Next comes a course of chemotherapy and radiation to try to destroy the remnants and roots of the tumor. This traditionally involves taking drugs orally or by injection. In the new procedure, called interstitial chemotherapy, six to eight biodegradable disc-shaped wafers, soaked with the anti-tumor drug carmustine, are placed in the affected area of the brain. This is done during the surgery, after the accessible part of the tumor has been removed. The drug is slowly released from the discs — each just 14mm in diameter and 1mm thick — over several weeks.
The wafers were developed at the Massachusetts Institute of Technology and went into use in 1996. "This is the first major new treatment for brain tumors in 22 years," says Pillay. In the U.S., brain tumors are the second-fastest-growing form of cancer in those over 65 and the No. 2 cause of cancer death among children under 15. Unlike the treatment now, in which the drugs run through the body to the brain, the medicated wafers attack the tumor directly. This circumvents the main obstacle to conventional brain-tumor chemotherapy — the blood-brain barrier, which filters out harmful substances before they reach the brain. This natural defense mechanism reduces the amount of medication able to reach the tumor.
The new procedure minimizes the side-effects associated with conventional chemotherapy. These side-effects, which arise when the drugs flow through the body, include anemia, severe nausea, hair loss and a drop in white blood cell count. And with direct application no drug is lost along the way, so the dosage can be reduced. Patients with lower tolerance for chemotherapy can particularly benefit.
Last year, Pillay performed the procedure for the first time in Asia. His two patients had advanced malignant tumors. Nine months later and more than two years after their initial diagnosis, both are recovering well. One has returned to work. But Pillay cautions that interstitial chemotherapy is not a one-stop cure-all. "This is a supplement to other treatments, not the sole method," he says. In European trials some 63% of patients were alive one year after surgery compared to 19% who did not get the wafers.
The wafer, essentially an innovative "on-site" delivery system for drugs, could also be effective with other types of cancers, as well as other diseases whose treatments have bad side-effects from chemotherapy. Says Pillay: "I expect that other agents can be introduced into the brain in a similar fashion to treat not only brain tumors but conditions like Alzheimer's disease, Parkinson's disease and epilepsy.
" The wafers may seem expensive, with a set of eight costing $8,000. But conventional chemotherapy has the possible extra expense of medicine needed to counter side-effects. Though the front-end costs of wafers are higher, says Pillay, they "actually end up cheaper." To those diagnosed with a brain tumor, the cost may not be important. The treatment may buy them something priceless: more time and perhaps an eventual cure. — By Andrea Hamilton
