DURHAM, N.C. - After investigating his options with his trademark intensity, Sen. Edward M. Kennedy underwent 31/2 hours of risky and exquisitely delicate surgery yesterday to cut out as much of his cancerous brain tumor as possible.

"I feel like a million bucks. I think I'll do that again tomorrow," the 76-year-old Massachusetts Democrat was quoted by a family spokeswoman as telling his wife immediately afterward.

Dr. Allan Friedman, who performed the surgery at Duke University Medical Center, pronounced the operation a success and said it "accomplished our goals." Up next: chemotherapy and radiation, aimed at shrinking whatever is left of the tumor.

"The main goal is to remove as much of the tumor as possible to give any other therapy that we do a better chance of working," said Dr. John Sampson, associate deputy director of Duke's brain-tumor center.

Kennedy was diagnosed last month with a malignant glioma, an often-lethal type of brain tumor discovered in about 9,000 Americans a year. Details about Kennedy's exact type of tumor have not been disclosed, but some cancer specialists said it might be a glioblastoma multiforme, an especially deadly and tough-to-remove type, because other kinds are more common in younger people.

Cutting a tumor down to size, or "debulking" it, is extremely delicate because of the risk of harming healthy brain tissue that governs movement and speech. But Friedman, who is the top neurosurgeon at Duke and an internationally known tumor surgeon, said Kennedy should not experience any permanent neurological effects.

Doctors said Kennedy was awake for much of the surgery, which begins with opening the scalp and removing a piece of the skull. Sometimes, to avoid damaging areas that control speech, surgeons use a probe to stimulate parts of the brain, then hold a conversation with the patient.

In the following days, Kennedy will probably receive drugs to prevent brain swelling and seizures, which are possible complications of the surgery. The senator will also be closely watched for bleeding and blood clots. He is expected to return to Boston in about a week.

"After a brief recuperation, he will begin targeted radiation at Massachusetts General Hospital and chemotherapy," Friedman said.

The outlook for patients with malignant gliomas is poor. Surgery is rarely a cure but is considered the best option for extending life.

Rep. William Delahunt (D., Mass.), a longtime friend, said Kennedy threw himself into helping find treatment options in much the same way he searched for cures when son Edward Jr. faced bone cancer at age 12 and daughter Kara had lung cancer five years ago.

He went so far as to pull Kara out of Johns Hopkins and took her to a Boston hospital when he was not satisfied with her treatment. In his own case, he met on Friday with family and doctors at Mass General and decided then to head to Duke for treatment.

Typical radiation treatment is five days a week for a month, using 3-D imaging techniques that narrowly deliver the beams to the tumor, affecting as little surrounding tissue as possible.

"After completing 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," Kennedy said in a statement issued before the surgery. He said he was "deeply grateful" for the "support and good wishes of friends, colleagues and so many others across the country and around the world."