Many of us may not have heard the term "malignant glioma" before today. In short, it's a cancerous brain tumor -- and the diagnosis now facing Sen. Edward Kennedy, D-Mass.
"This is very bad news," said Dr. John A. Wilson, associate professor of neurosurgery at Wake Forest University School of Medicine in Winston-Salem, N.C.
The word glioma comes from "glia," the gluelike cells that hold the brain together, said Dr. Lynne Taylor, a fellow with the American Academy of Neurology. A glioma is a primary brain tumor, one that begins in the brain without spreading from another location in the body. The word "malignant" indicates that it's both cancerous and rapidly growing.
Malignant gliomas make up more than half of the 18,000 primary malignant brain tumors diagnosed in the United States each year, according to the National Cancer Institute. The tumors are graded from I to IV according to severity, with Grade IV being the most aggressive tumor. The NCI estimates that the median survival for Grade III tumors is three to five years, and less than a year for Grade IV.
Because of the 76-year-old senator's age and the fact that the tumor is labeled as malignant, it's likely a Grade III or IV tumor, according to Dr. Nina Paleologos, chair of the section of neuro-oncology for the American Academy of Neurology.
To identify the tumor's type, surgeons at Massachusetts General Hospital performed a brain biopsy, in which surgeons remove a small amount of tissue from the brain. If the tumor can be removed without injury to the brain, it is often removed completely, said Dr. Clifford B. Saper, chairman of the department of neurology at Beth Israel Deaconess Medical Center in Boston.
In Kennedy's case, they didn't remove it. There could be two reasons for that decision: Either doctors wanted to figure out the type of tumor before they rushed to surgery, or the tumor was too difficult to remove, according to Paleologos.
"Without seeing his pictures, it's too hard to say," she said.
The tumor's location -- the left parietal lobe of the brain -- may make its removal tricky. The left parietal lobe is located above the left ear, and if Kennedy is right-handed, the left side of his brain is dominant. It controls much of his movement and sensory capabilities on the right side, as well as his speech.
"My suspicion is that's what they are concerned about," Paleologos said. Surgeons would be wary of performing surgery in an area that could disrupt Kennedy's speaking abilities.
Some doctors are not surprised by the diagnosis, especially after Kennedy's seizure Saturday morning.
"If anyone over the age of 21 has a seizure for the first time, they have a brain tumor until proven otherwise," said Dr. Gerald Rosen, a neuro-oncologist from St. Vincent's Comprehensive Cancer Center.
However, Kennedy's seizure may actually be a positive sign, said Dr. Henry Brem, chairman of neurosurgery at Johns Hopkins. "It means the brain itself is intact," he said. If the senator had experienced paralysis, he might have already suffered brain damage.
The tumor may be relatively new, but growing fast. Six months ago Kennedy had surgery for a narrowing of his left carotid artery. Brem believes doctors may have performed an MRI scan before that surgery, which would have caught the tumor if it were present.