WASHINGTON — Sen. Edward M. Kennedy underwent a 3 1/2 -hour surgery at Duke University Medical Center on Monday to remove a malignant brain tumor, the first step in what is expected to be weeks or months of therapy.
The surgery "was successful and accomplished our goals," Kennedy's neurosurgeon, Dr. Allan Friedman, said in a statement from Durham, N.C.
Friedman said Kennedy was conscious throughout the procedure and should experience no permanent neurological effects from the surgery.
A Kennedy spokesman said the senator spoke with his wife, Victoria Reggie Kennedy, immediately after the surgery and told her: "I feel like a million bucks. I think I will do that again tomorrow."
In a statement issued by his office, the 76-year-old Democrat said the surgery would be followed by radiation treatments at Massachusetts General Hospital, as well as by chemotherapy.
Saying he was "humbled by the outpouring" of prayers from around the world, the senior senator from Massachusetts thanked those who had "expressed their support and good wishes as I tackle this new and unexpected health challenge."
The liberal lion of the Senate, who endorsed Sen. Barack Obama of Illinois for president in February, said that after completing his treatment, "I look forward to returning to the United States Senate and to doing everything I can to help elect Barack Obama as our next president."
During a Senate debate Monday on a global warming bill, Sen. Barbara Boxer (D.-Calif.) interrupted the proceedings to read a statement from Kennedy's physician and asked the group to pause a moment in prayer for their colleague.
Kennedy was diagnosed last month with a malignant glioma, one of the most lethal forms of brain cancer. About 9,000 people contract it in the U.S. every year, with most dying within two years after diagnosis.
Many experts were surprised that Kennedy chose Duke for the surgery because Boston is home to so many excellent medical centers. One possibility is that he went there because of Friedman's work on therapeutic cancer vaccines.
Although few details about the nature of his tumor or the surgery have been released, experts described what might be considered a typical procedure.
The surgery was intricate, complicated by the fact that the tumor cells can be difficult to distinguish from surrounding brain tissue and because the tumor is close to centers of the brain that control motor function, speech and memory.
On Sunday night, before the surgery, Kennedy most likely underwent an MRI, which allowed surgeons to generate a three-dimensional map of the tumor.
Friedman and his team would have referred to the map frequently during the procedure, and may have used more imaging during the operation to ensure that they removed as much tumor as possible. Many neurosurgical operating suites have an MRI or CT scanner in the room for easy access.
Kennedy was then placed under deep sedation, but not rendered unconscious.
After pulling back a flap of outer skin and cutting through the skull and the dura -- the membrane surrounding the brain -- the team would have identified important speech and motor areas near the tumor.
"Everybody is wired slightly differently," said Dr. Mike Y. Chen of the City of Hope Comprehensive Cancer Center in Duarte, so surgeons have to map the areas precisely.
Motor areas can be located in one of two ways: Surgeons can use a small electrode on the patient's wrist to send a signal that can be detected in the brain.
"Once you know the location of the signal from the wrist, you can extrapolate to where others are located," said Dr. Keith L. Black, chairman of the department of neurosurgery at Cedars-Sinai Medical Center in Los Angeles.
Alternatively, surgeons can use an electrode to apply minute electrical currents to brain tissue to check for leg or arm movements and map motor control that way.
If the tumor were near a speech center, Kennedy would have been asked to talk, such as by counting, while surgeons used an electrode to apply minute currents to the brain. If his speech were suddenly interrupted, they would know that they had found the speech center.
Then, typically working under a microscope, the neurosurgeon would begin removing tumor cells. Because gliomas usually do not have sharp margins between the tumor and normal brain tissue, it is not possible to simply cut around the edges and remove them.
Doctors probably sent a sample slice to a pathology lab for confirmation of the diagnosis.
They might also have removed a larger section to be used in vaccine preparation or to check for genetic markers that might be useful in choosing chemotherapy drugs.
They would then have begun nibbling away at the tumor a little bit at a time, possibly using electrocautery to burn away tumor cells or an ultrasonic aspirator that breaks down the tumor cells and sucks them out.