Sept. 20, 2011 -- The heart attack death of Kara Kennedy, the latest in the tragedy-touched Kennedy dynasty, may have been related to the aggressive cancer treatment she underwent about a decade ago, say her brother and a cardiologist.
The 51-year-old daughter of the late Sen. Edward M. Kennedy died Sept. 16 while working out at her Washington, D.C., gym.
"Depending upon where the lung cancer was, her heart could have taken a direct hit," said Dr. Sharonne N. Hayes, a cardiologist and founder of the Women's Heart Clinic at the Mayo Clinic.
More details on Kara Kennedy's death are expected to be released by the Edward M. Kennedy Institute for the United States Senate as funeral arrangements are being made for Wednesday.
Kara Kennedy was diagnosed with lung cancer in 2002 and was initially told it was inoperable. But with her father's help, she found a surgeon at Brigham and Women's Hospital in Boston who removed part of her right lung, followed by chemotherapy and radiation.
Her brother, former Rhode Island Rep. Patrick Kennedy, 44, said the grueling treatments had left his sister physically weakened.
"Her heart gave out," he told the Associated Press. "She's with dad."
Their father died of a brain tumor in 2009. Kara Kennedy's younger brother, Edward Jr., lost a leg to cancer as a child in 1973. Patrick Kennedy had surgery in 1988 to remove a noncancerous tumor from his spine.
For cancer patients who have aggressive chemotherapy and radiation, particularly in the chest, "there are some real heart risks," according to cardiologist Hayes, who did not treat Kara Kennedy. "The heart muscle can be weakened."
"This is probably widely underappreciated," she said. "People are so fearful of cancer, but in order to save people from cancer, other organs are put at risk -- the heart, in particular."
Her mother, Joan Bennett Kennedy, 75, said Kara Kennedy had fully recovered from cancer and led an active life, swimming and walking on the beach. "She was very healthy," her mother told the Associated Press. "That's why this is such a shock."
But others said that recently the late filmmaker recently did not look well.
"She was painfully thin," said one of Kara Kennedy's neighbors in Bethesda, Md., where Kennedy, who was recently divorced, lived. "After the illness, she looked aged. She avoided the spotlight and was definitely an exercise devotee."
Kennedy, who was also a television producer, had been married to professional sailor Michael Allen for 11 years, and their two children, Grace Kennedy Allen, 17, and Max Greathouse Allen, 15, lived with their father, according to neighbors.
Allen told the Associated Press that his ex-wife swam at her health club almost every day.
"The kids seemed really normal and happy," said one neighbor, who did not want to be identified. "They lived an average life, and she seemed very close to them."
The Kennedy family, including Kara Kennedy's mother, brother and some of the cousins, had a history of alcohol and drug abuse. She was instrumental in founding the National Organization on Fetal Alcohol Syndrome in 1990, where she sat on the board of directors.
"Because of her, the whole issue of drinking and pregnancy has been brought to the spotlight," Cathleen Mitchell, a spokeswoman for the organization, told the Boston Herald. "It would be hard to measure the number of lives she touched."
Doctors said that many things -- including alcohol and cocaine abuse, anorexia, as well as cancer treatments could contribute to an early heart attack.
Certain types of chemotherapy can weaken the heart muscle temporarily or permanently. Radiation can also affect the heart muscle and the pericardium, the sac around the heart.
"It also accelerates the aging process," said Hayes. "We as cardiologists learn of new side effects of these drugs when they reach middle age. We see [heart disease] at 51 that we would see at 66."
One chemotherapy drug -- adriamycin, which is in a class of anthracylines -- can be especially toxic to the heart, she said. "We have known about heart toxicity for decades and try to limit doses."
Lung cancer treatments can cause blockages or a sudden heart attack, which could be exacerbated if a patient ever smoked or has heart disease. They can also cause heart rhythm abnormalities.
Those who have been treated for Hodgkins disease as children, lung cancer and left-sided breast cancer can be particularly vulnerable to later cardiovascular disease.
"For women, it's a no-win," said Hayes. "They survived breast cancer 20 years ago and thought it was a miracle. Then they develop radiation-induced heart disease."
Women may also be more vulnerable to treatments, according to Hayes. "We don't have good data because a lot of times they don't separate it out by gender. They have smaller arteries to start with and a smaller body size. We don't fully understand the sex differences."
As for Kennedy's workout, during which the heart attack happened, doctors have long known that certain arrhythmias could be provoked by exercise.
Though Kennedy was also thin, doctors said it was hard to know if that was part of a healthy lifestyle or a sign of an underlying health condition. "The esophagus is within the range [of the lung] and some people who have radiation for lung cancer end up with an esophagus [problem] and it's harder to eat," said Hayes.
Heavy alcohol use can also contribute to a weakening of the heart muscle, and drugs like cocaine can cause an acute heart attack from elevated blood pressure.
"We are curing more people and giving them newer drugs to let them live well with cancer," said Hayes. "But there are lots of costs."
One of Hayes' patients found that the drug that worked so well controlling his spindle cell cancer for a decade landed him with heart failure. "We had to stop, and it was a gut-wrenching decision -- to die or the cancer won't be controlled," she said.
Hayes is currently treating a woman in her 60s whose deadly inflammatory breast cancer was cured by radical treatments in her 30s. But by 55, she had developed severe heart valve disease because of heavy radiation doses. Now, at 60, she is on a ventilator for heart and lung problems.
"I think she will come through it," said Hayes. "If asked, she would never say she regretted having the 20 years to see her children grow up and to have grandchildren. But this reality pushes us cardiologists to be aware and deal with the side effects. And it pushed our cancer colleagues to come up with treatments that are more specific to the disease and less toxic."