Sen. Ted Kennedy has a malignant brain tumor known as glioma, according to a diagnosis made Tuesday by doctors at Massachusetts General Hospital. Kennedy has been released from the hospital and will return to his home on Cape Cod in Massachusetts.
The most common form of brain tumor, gliomas rank among the hardest to treat and can grow “very rapidly” in their most malignant form, neuroscientists say.
“Everything around them is very important tissue,” said Kavita Dhodapkar, a researcher at Rockefeller University who studies brain tumors and the immune system. “You can’t surgically remove them as easily as some other tumors (outside the brain).”
That’s also because they are “infiltrating” tumors, said Alessandro Olivi, director of neurosurgical oncology at Johns Hopkins University School of Medicine. The margins of such tumors are difficult to distinguish, Olivi said.
In several studies of glioblastomas (grade 4 glioma), cancer has been shown to reappear and grow beyond the area of removal, she said.
Senator Kennedy suffered a seizure May 17 that led to his hospitalization and the discovery of the tumor. Seizures are a common initial sign of brain tumors, which account for about 1.3 percent of all cancers, according to the American Cancer Society.
Kennedy’s tumor is located in the left parietal lobe, according to his doctors. Specific areas within the parietal lobe are associated with motor function, the integrity of the visual field and speech, Olivi said. If a tumor in the region progresses, cognitive function can be affected, he added.
“This is a serious problem that we know is most likely in an ‘eloquent’ area of the brain … a part of the brain that is controlling a specific and important area of the body,” Olivi said.
If the area is a vital one, surgery would be very difficult. In most cases, however, “surgery is the first option,” Dhodapkar said. “Most people will undergo surgery followed by radiation therapy,” sometimes in combination with chemotherapy.
Doctors have not commented on whether Kennedy might have surgery. Nor have they released information about the severity of Kennedy’s tumor other than to identify it as malignant, which leads Olivi to speculate that it is either grade 3 or 4 on a scale of 1 to 4. Grade 4 tumors can grow “very rapidly,” Dhodapkar said.
A grade 4 tumor is associated with an average life span of one to two years, Olivi said, while patients diagnosed with grade 3 tumors live two to three years on average.
Age, as well as grade and the ability to remove the tumor surgically, can affect the outcome with these tumors. “Younger patients tend to do better [in treatment] than older ones,” said Dhodapkar. At 76, Kennedy faced an increased risk of contracting glioma.
No known cause, no known cure
Glioma originates in the brain and is defined by the cells it attacks: glial cells, which Olivi defined as “the cells that support brain tissue.”
As with other brain tumors, “We don’t actually know what causes these [gliomas],” said Dhodapkar.
They do occur with greater frequency in children who have had radiation for other cancers, she said, “but that is not what happens in most adults who get it.”
Beyond the lower grades of glioma, no complete cure is known. “Treatments are palliative,” Olivi said.
Nor does surgery guarantee permanent removal of cancer cells, Dhodapkar added. Recurrence rates can be very high for more malignant tumors. Even after surgery, radiation treatments and chemotherapy, “it is quite likely that it will come back if it is a higher grade,” said Dhodapkar.
Dhodapkar cited cancer society statistics estimating that approximately 21,810 malignant tumors in the brain or spinal cord will be diagnosed this year, of which about 13,070 will lead to death.
Dan Gordon contributed to this report.