Kara Kennedy, the oldest child of the late Sen. Edward Kennedy, died suddenly Friday evening at a Washington-area health club.
Former Rep. Patrick Kennedy confirmed the death of his 51-year-old sister, adding "she's with dad."
Kara Kennedy had herself battled lung cancer: In 2003, doctors removed a malignant tumor. Patrick Kennedy said that his sister loved to exercise, but that he thinks her cancer treatment "took quite a toll on her and weakened her physically."
"Her heart gave out," he said.
Kara Kennedy was the oldest of three children. She and her brother Edward Kennedy Jr. helped run their father's U.S. Senate campaign in 1988. The National Organization on Fetal Alcohol Syndrome lists her as a national advisory board member on its website.
Edward Kennedy Jr. himself was a survivor after losing a leg to bone cancer as a child. And Patrick Kennedy had surgery in 1988 to remove a non-cancerous tumor that was pressing against his spine.
In 1990, Kara Kennedy married Michael Allen. The couple have two children: Max Greathouse Allen, 15, and daughter, Grace Kennedy Allen, 16.
Kara Kennedy was born in 1960 as her father campaigned for his brother, John F. Kennedy, during the presidential primaries.
The late senator wrote in his 2009 memoir, "True Compass," that "I had never seen a more beautiful baby, nor been happier in my life."
She was diagnosed with lung cancer in 2002 and was given a grim prognosis by doctors, her father wrote. She had an operation in 2003 that doctors said was successful, and Edward Kennedy accompanied his daughter to chemotherapy treatments.
In the book, Edward Kennedy recalled her operation, along with her aggressive chemotherapy and radiation treatments.
"Kara responded to my exhortations to have faith in herself," he wrote. "Today, nearly seven years later as I write this, Kara is a healthy, vibrant, active mother of two who is flourishing."
In 2009, shortly before his death, Edward Kennedy was awarded the Presidential Medal of Freedom by Barack Obama. Kara Kennedy accepted the award on behalf of her father.
'Part of something larger'
Five months before her death, Kara Kennedy wrote of her father and the institute named in his honor in an article published in The Boston Globe Magazine. She described Christmas 1984, when her father insisted on spending the night helping relief workers feed hungry people in the Ethiopian desert. And of how each summer, Ted Kennedy loaded the family into a Winnebago for road trips to hike through historic battlefields and buildings.
She wrote of family trips in the summer when the late senator would lead his children on explorations of historic battlefields and buildings, trips she said taught her that one person can make a difference.
"What mattered to my father was not the scale of an accomplishment, but that we did our share to make the world better," she wrote. "That we learned we were part of something larger than ourselves."
Kara Kennedy, a graduate of Tufts University, also worked as a filmmaker and in television. She helped produce several videos for Very Special Arts, an organization founded by her aunt Jean Kennedy Smith. She also served as a board member for the Edward M. Kennedy Institute; director emerita and national trustee of the John F. Kennedy Library Foundation; and as a national advisory board member for the National Organization on Fetal Alcohol Syndrome.
The New York Times noted that many members of her generation of the Kennedy family have died relatively young: John F. Kennedy Jr., killed in a 1999 plane crash; Michael L. Kennedy, killed in a 1998 skiing accident; his brother David, who died of a drug overdose in 1984. The Times also noted that her father was the only one of four brothers to live to old age.
In addition to her children, she is survived by her mother, Joan Kennedy, and younger brothers, Edward Kennedy, Jr., and Patrick Kennedy and their families.
The Associated Press contributed to the report.