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Heart of the Matter: Cardiac Toxicity

Patients should be aware of possible cardiac toxicities & what to do about them.

BY KATHY LATOUR
PUBLISHED MONDAY, JUNE 17, 2013
In 2002, Katharine Ray, a 27-year survivor of Hodgkin lymphoma, wanted work "that mattered" when she joined the staff of The Minnie Pearl Cancer Foundation (now PearlPoint Cancer Support) in Nashville, Tenn. A year later, at age 42, she received a diagnosis of stage 1 breast cancer, probably a result of radiation treatments she received when she was 14.

The diagnosis served as an important point of demarcation for Ray, who had never really processed what happened to her as a teenager.

"I had been there a year and was just beginning to understand my chances for a second cancer, and then it happens, and it's reality," she says. "I began looking past the breast cancer treatment & began gathering all the information I could find for late effects from the Hodgkin treatment going forward."

Ray took her research on possible late effects and, with her oncologist, made a plan for how she should be followed in the areas where she could be at risk.

She had noticed that at times her heart beat rapidly, and she was getting easily winded while climbing stairs or taking walks that involved any kind of incline. All her test results were normal, but in 2012 she decided to see a cardiologist who would understand what to look for when considering her medical history. She didn’t have to look far.

Across town from PearlPoint, cardiologist Daniel Lenihan directed the clinical research program at Vanderbilt University Medical Center in the division of cardiovascular medicine. In 2009, he cofounded the International Cardioncology Society (ICOS) with a goal to promote training and study in the field of cardiac implications of cancer treatments.

Lenihan is one of a growing number of cardiologists who focuses on cancer patients. This partnership of cardiologists and oncologists combines their knowledge to protect the hearts of people undergoing cancer treatment—patients such as Katharine Ray.

People who have survived cancer are at risk for a number of cardiac long-term and late effects linked to radiation and chemotherapy treatments, ranging from high blood pressure on one end of the spectrum to congestive heart failure on the other.

Radiation treatment can cause a thickening of the inner lining of the artery, known as atherosclerosis, which can cause blood clots and other problems associated with narrowed arteries and reduced blood flow. Chemotherapy and radiation may also cause structural heart problems, such as cardiomyopathy (weakening of the heart muscle), valvular heart disease and valvular degeneration, as well as pericardial effusion (a buildup of fluid around the heart) or pericardial constriction (an abnormal thickening of the lining enclosing the heart).

In addition, not only is radiation for Hodgkin lymphoma at a young age now recognized as a risk factor for later heart problems but also for breast cancer. In the past two decades, as these issues have come to light, patients with Hodgkin disease, as well as others receiving radiation treatments, now receive lower total doses of radiation, smaller doses given more often (hyperfractionation), cardiac shielding and education about following a heart-healthy lifestyle.

While changes in procedures and reductions in the amount of radiation have, presumably, reduced radiation’s toxic effects, a recent study of 2,168 women treated between 1958 and 2001 in Sweden and Denmark confirmed that "exposure of the heart to ionizing radiation during radiotherapy for breast cancer increases the subsequent rate of ischemic heart disease." The study, which appeared in a March issue of The New England Journal of Medicine, found the increase was proportional to the average dose to the heart, that it began a few years after exposure and continued for at least 20 years.

In an accompanying editorial, Javid Moslehi, co-director of the cardio-oncology program at Brigham and Women's Hospital and Dana-Farber Cancer Institute in Boston, pointed to radiation as one of the effective treatment strategies that has led to the decrease in breast cancer mortality since 1990. He also called for preventive cardiovascular medicine before treatment to reduce atherosclerosis.

"The current study points to radiation therapy as a significant risk factor for coronary disease in patients with breast cancer," he wrote. "This finding suggests that cardiac risk factors should be assessed and aggressively managed—starting at the time of radiation treatment (or even before) and continuing throughout survivorship."

Cardiac risk factors should be assessed and aggressively managed—starting at the time of radiation treatment (or even before) and continuing throughout survivorship.

Of the chemotherapy agents with cardiac toxicities, anthracyclines (particularly doxorubicin) have been studied most, and it appears that 1 percent of all cardiomyopathy cases (a weakening of the heart muscle, which can lead to heart failure) are linked to their use.

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