Sen. Kennedy waves as he leaves Massachusetts General Hospital, 21 May 2008

The office of Democratic Senator Edward Kennedy says the senior lawmaker is recuperating well following surgery on a cancerous brain tumor.

The senator's office said in a statement Tuesday that the 76-year-old lawmaker from Massachusetts is experiencing no complications, one day after undergoing 3.5 hours of surgery at Duke University Medical Center, in Durham, North Carolina.

It said Senator Kennedy has been walking the hallways, spending time with his family and actively keeping up with the news of the day.

Duke University Medical Center in Durham, North Carolina

Kennedy was diagnosed with the malignant brain tumor after suffering a seizure last month at his home in Massachusetts. It was not clear how much of the tumor, known as a glioma, was removed, but Kennedy's surgeon, Allan Friedman, has described the surgery as a success and that it, in his words, "accomplished our goals."

Kennedy is expected to be hospitalized for about a week, then return to Massachusetts to begin radiation and chemotherapy treatments.

Medical experts say this type of cancer is particularly serious and half the people diagnosed with it die within a year.

Kennedy was first elected to the Senate in 1962. The liberal lawmaker is the second-longest serving U.S. senator currently in office and the sole surviving son of one of America's most famous political families. Two of his brothers, President John F. Kennedy and Senator Robert Kennedy, were both assassinated in the 1960s. Another brother, Joseph Kennedy, was killed while serving in World War II.

Separately, the longest-serving senator, Democrat Robert Byrd of West Virginia, was also under hospital care Tuesday. Byrd's office says the 90-year-old lawmaker will remain hospitalized for several more days in the Washington area for treatment of a mild infection.

Byrd was taken to the hospital Monday after appearing lethargic and suffering a fever.

Some information for this report was provided by AP and Reuters.