By Brian C. Mooney, Globe Staff
US Senator Edward M. Kennedy has been diagnosed with a malignant brain tumor, his doctors said Tuesday, and the prognosis appears uncertain at best for the last surviving brother of the famed Kennedy clan, who has been an enormous force in American politics for nearly half a century.
The announcement was made three days after Kennedy, 76, was stricken at the family’s Hyannis Port compound. Doctors at Massachusetts General Hospital conducted a battery of tests, including a biopsy, and identified a cancerous mass on the top left portion of his brain as the cause of his seizure.
The news sent shockwaves across Massachusetts, which he has represented in the Senate for more than 45 years, and across Washington, where he is held in high esteem by Democrats and Republicans alike. Many of his Senate colleagues were visibly shaken, some tearing up, and they quickly expressed their hope for the best possible outcome.
‘‘The usual course of treatment includes combinations of various forms of radiation and chemotherapy,’’ said a statement by Dr. Lee Schwamm, a neurologist, and Dr. Larry Ronan, Kennedy’s primary care physician.
But the two Mass. General physicians added that decisions about the best course of treatment would be made after more tests and analysis. They described the senator as ‘‘in good overall condition ... up and walking around the hospital ... in good spirits and full of energy.’’
While his doctors said he will remain at Mass. General ‘‘for the next couple of days,’’ Kennedy associates said they expected him to push for his discharge as early as Wednesday.
The prognosis is highly variable at best, ominous at worst, and it raises the possibility that the workhorse lawmaker will be unable to complete the final years of his eighth full term.
Despite the bad news, a Kennedy associate said that the senator shows no symptoms, remains upbeat, and has warned small groups of aides that he wants them back at work.
The associate, who requested anonymity, said Kennedy is plotting his course of treatment as if he were mapping strategy to enact a major piece of legislation, peppering his doctors with questions and planning to reach out to other specialists before determining a course of action.
He has given no thought to retirement, a Kennedy confidant asserted. ‘‘It’s not even an option.’’
Kennedy’s type of cancer, known as a malignant glioma, is the most common kind of brain tumor in his age group. About 9,000 such malignancies are diagnosed each year in the United States.
Dr. Patrick Wen, clinical director for neuro-oncology at the Dana-Farber Cancer Institute, called a malignant glioma, in general, ‘‘a really serious tumor,’’ usually Grade 3 or 4 on a scale where 4 is most severe.
‘‘The average survival for a Grade 4 tumor is 14 or 15 months,’’ Wen said. ‘‘For a Grade 3 tumor, it’s two to three years. Unfortunately, the older you are, the worse it is. The biology of the tumor is worse, it’s more aggressive."
If Kennedy is unable to serve, a special election to choose a successor would be held between 145 and 160 days after the seat becomes vacant, according to a state law enacted in 2004.
Kennedy, the second-longest serving member of the Senate and third-longest serving in its 219-year history, has had a series of health problems over the years. Six months ago he underwent surgery to repair a partially blocked carotid artery in his neck. But he has continued to maintain a vigorous schedule.
The senator and his wife, Victoria Reggie Kennedy, were given the diagnosis late Monday by his doctors.
His wife arrived yesterday at Mass. General at 6:20 a.m., stepping out of a black sport utility vehicle and walking briskly inside. His sons, Edward M. Kennedy Jr. and US Representative Patrick Kennedy of Rhode Island, arrived at 9:45 a.m. Kara Kennedy, his daughter, also spent yesterday at the hospital, as did Kennedy’s two stepchildren, Curran and Caroline Raclin.
None of the Kennedys talked to the reporters standing watch outside. Neither the family nor Kennedy’s office issued public statements, but late in the day they allowed photographers from the Globe and Associated Press to shoot pictures of Kennedy and members of his family.
Once the announcement was made, in the form of an e-mail to reporters, reaction was broad, swift, and solemn. Dana Perino, Bush’s spokeswoman, said the president ‘‘was deeply saddened and would keep Senator Kennedy in his prayers.’’
Kennedy’s hospitalization Saturday triggered alarm in the political world and drew an outpouring of support from around the nation. The concern abated when friends and associates said later that day that he was talking and joking with family, watching the Red Sox on television, and getting takeout from Legal Sea Foods.
But as word of the new diagnosis traveled quickly yesterday, his constituents expressed sadness upon hearing the news.
‘‘Oh, my God,’’ said Lisa Rappoli, 55, of Belmont. ‘‘It’s a shock, just a shock.’’
‘‘I just felt sorrow, but I’m praying, wishing that he has at least a good chance,’’ said Angelo
Vespa, 43, of Newton. ‘‘All that he’s gone through, it’s really said.’’
Since being elected to the Senate in 1962 to the seat vacated by his brother, President Kennedy, Edward Kennedy has sponsored more than 2,500 bills, with nearly a quarter becoming law. He has made a career of championing the causes of the least fortunate in American society. His ability to forge bipartisan agreement has brought sweeping changes to entire sections of federal law dealing with healthcare, mental health, the disabled, early childhood education, labor, civil and voting rights, and immigration. His first major speech on the Senate floor was in support of the Civil Rights Act of 1964.
To Massachusetts, Kennedy has helped bring enormous sums of money for funding medical and other scientific research, infrastructure, historic preservation, and aid for the state’s older cities.
A summary of Kennedy’s achievements in the Senate, compiled by his staff, is 50 single-spaced pages long. ‘‘That’s the trimmed-down version,’’ an aide said recently.
During President Bush’s administration, Kennedy was an early and consistent critic of the Iraq war, but also an important ally who helped Bush win passage of No Child Left Behind, the education law that was a signature achievement early in Bush’s first term.
Kennedy is the only one of the four brothers to live through middle age. His three brothers all died prematurely: Joseph P. Kennedy Jr., killed in 1944 on a World War II bombing mission; John F. Kennedy, assassinated in Dallas in 1963; and Robert F. Kennedy, assassinated while campaigning in Los Angeles in 1968.
Political success and personal tragedy have marked the epic story of one of the nation’s most famous families. Edward Kennedy’s son, Patrick, and nephew Joseph P. Kennedy II became congressmen, and a niece, Kathleen Kennedy Townsend, served as lieutenant governor of Maryland.
Three other nephews died tragically — John F. Kennedy Jr. in a plane crash, Michael Kennedy in a skiing accident, and David Kennedy from a drug overdose. Two of Edward Kennedy’s children, Edward Jr. and Kara, are cancer survivors.
Kennedy has suffered through his own misfortune and failure. In 1964, he suffered a broken back in a small plane crash in Western Massachusetts that resulted in the death of the pilot and one of Kennedy’s aides. In 1969, Mary Jo Kopechne drowned when a car driven by Kennedy went off a bridge on Chappaquiddick Island, and Kennedy left the scene. His marriage to his first wife, Joan, ended in divorce in 1982, and as the third Kennedy brother to seek the presidency, he lost a 1980 challenge to Jimmy Carter, the incumbent from his own party.
Seven years later, he abandoned any ambition to the presidency when he announced he would run for reelection to the Senate.
‘‘I know that this decision means that I may never be president,’’ he declared. ‘‘But the pursuit of the presidency is not my life. Public service is.’’
Carey Goldberg and David Abel of the Globe staff and Globe correspondent Matthew Collette contributed to this report.