WASHINGTON — Sen. Edward M. Kennedy will undergo surgery this morning at Duke University Medical Center for his cancerous brain tumor and then faces chemotherapy and radiation treatment, his office said.

The 76-year-old senator was diagnosed last month with a malignant glioma, an especially lethal type of brain tumor. A statement from the Massachusetts Democrat's office said he would be operated on this morning in Durham, N.C., by one of the nation's top neurosurgeons, Dr. Allan Friedman, followed by chemotherapy and radiation.

Anthony Coley, a Kennedy spokesman, said the surgery is scheduled to begin around 9 a.m. and expected to last about six hours. He expects to remain at the North Carolina facility for one week to recuperate and then will begin further treatments at Massachusetts General Hospital and start chemotherapy.

"I am deeply grateful to the people of Massachusetts and to my friends, colleagues and so many others across the country and around the world who have expressed their support and good wishes as I tackle this new and unexpected health challenge," Kennedy said in the statement. "I am humbled by the outpouring and am strengthened by your prayers and kindness."

Kennedy said that over the past few days he and his wife, Vicki, "along with my outstanding team of doctors at Massachusetts General Hospital, have consulted with experts from around the country and have decided that the best course of action for my brain tumor is targeted surgery followed by chemotherapy and radiation."

Kennedy said he selected a team of neuro-oncologists from Boston's Massachusetts General Hospital and Duke University Medical Center.

Friedman is "one of the thought leaders" and a giant in the field of neuro-oncology, said Dr. Otis Brawley, chief medical officer of the American Cancer Society, speaking from Chicago, where more than 30,000 cancer specialists are attending an American Society of Clinical Oncology conference.

Friedman is chief of the division of neurosurgery in the surgical department at Duke and also co-director of the neuro-oncology department there. His clinical interests are brain tumors, skull-based tumors, peripheral nerve surgery, pituitary tumors and cerebrovascular disaster, according to his resume on the medical center's Web site.

After his treatment, Kennedy said, "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 has endorsed Obama, the front-runner for the Democratic presidential nomination.

Kennedy was hospitalized May 17 at Massachusetts General Hospital after undergoing a seizure at his home on Cape Cod. Doctors later announced that he had a malignant glioma in his left parietal lobe, a brain region that governs sensation but also plays some role in movement and language.

Malignant gliomas are diagnosed in about 9,000 Americans a year. In general, half of all patients die within a year. The brain tumor research center at Duke is conducting several clinical trials in malignant glioma.

Kennedy likely will receive the chemotherapy drug Temodar during and after radiation, said Brawley. The pivotal study showing the drug's value for brain tumors was presented three years ago at the clinical oncology conference. Kennedy also may be treated with Avastin, a newer targeted drug to deprive the tumor of its blood supply, though this is still experimental at this stage of treatment.

Median survival for glioblastomas is 12 to 15 months, but the range is wide, said Dr. Mark Gilbert, a brain tumor expert at the University of Texas M.D. Anderson Cancer Center in Houston.

When operating, "the surgeon usually does as much as possible within the bounds of safety. We do not want to do neurological damage in an effort to remove as much of the tumor as possible," Gilbert said.

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.

Kennedy has a history of seeking top medical care available for his family. He pulled daughter Kara out of Johns Hopkins and brought her to a Boston hospital when he was not satisfied with the initial course of treatment she was getting for lung cancer five years ago.

In addition to his congressional health insurance plan, which is often described as one of the most generous in the country, Kennedy's wealth gives him the means to afford the best possible health care. The senator is known to reach into his own pocket and pay supplemental salary to staffers who otherwise might be tempted to leave his office for better paying jobs.