Heart disease stalks breast cancer survivors
Survivors of breast cancer are living so long that they face another risk — heart disease, and it’s being brought on by the drug treatments that saved their lives
WHEN Susan Heun showed up at Froedtert Hospital, in Wauwatosa, Wisconsin, last month, all she wanted was a second opinion on her breast cancer. She wasn’t expecting that heart doctors would get involved in her treatment.
Heun, 58, collapsed and went into cardiac arrest at the hospital while awaiting routine tests. She was revived, only to get disturbing news: her heart was not pumping as well as it should, which might have been the result of the breast cancer treatments she received a couple of years earlier.
‘‘ Now I’m going home with heart medication,’’ Heun said while lying in her bed at the hospital, with her husband, Tom, sitting next to her. ‘‘ I didn’t come in with heart medication. Now we’ve got two problems.’’
For years, physicians have known that some chemotherapy drugs and radiation can damage the heart. But doctors and patients have ratcheted up their concern as cancer patients live longer and as alternative therapies less toxic to the heart have become available.
‘‘ In the old days, cardiac death (for cancer patients) was a blessing,’’ said Byung-il William Choi, a Froedtert cardiologist. ‘‘ No more.’’
Recent research published in the Journalof theAmericanCollegeofCardiology suggested that breast cancer patients might be at even higher risk because of what’s known as the ‘‘ multiple-hit’’ hypothesis.
The authors noted that physical inactivity and obesity — two independent risk factors for breast cancer and heart disease — are more common in breast cancer patients. Then, add in the various therapies breast cancer patients must go through. The result is a series of ‘‘ cardiovascular insults’’, the authors wrote.
The insults, or damaging effects, make the heart even more susceptible to injury and the patient more at risk of dying prematurely.
Heun’s situation is complicated. Froedtert doctors say they do not think her cancer treatments led to the arrhythmia that caused her heart to stop. However, they found another problem with her heart that they do believe was caused by the cancer treatments: her heart wasn’t pumping efficiently.
Cardiologists use a measure known as ejection fraction to describe how much blood is pumped out of the left ventricle, the heart’s main pumping chamber, with each beat. A normal ejection fraction is 55 per cent to 75 per cent. Heun’s ejection fraction is 35 per cent, indicating damage to the heart muscle and a condition known as heart failure.
‘‘ I knew that the chemotherapy and the radiation had something to do with this,’’ said cardiologist Choi.
Twenty-five years ago, Choi co-wrote a paper in the American Heart Journal highlighting the cardiovascular concerns of a particular cancer drug and offering recommendations on how and when it should be used to limit heart damage.
Today, with 2.3 million American women living with a history of breast cancer and a 24 per cent drop in the breast cancer death rate alone from 1990 to 2000, the concern is even more magnified.
More and more doctors are looking to replace old-line cancer drugs that have known toxic heart effects with ones that might work as well but without the heart problems, said Jim Stewart, an oncologist at the University of Wisconsin Hospital and Clinics in Madison.
‘‘ We have to assume that a woman with breast cancer will be alive 20 or 30 years later,’’ said Stewart.
Indeed, since ageing is an independent risk factor for heart disease, longer survival for breast cancer patients who also might have been exposed to heart-damaging drugs is likely to mean more cases of cardiovascular disease in the years to come.
‘‘ It’s a reflection of success,’’ Stewart said. ‘‘ They are surviving long enough to be at risk.’’
In September, a study of 43,338 older women treated for breast cancer between 1992 and 2002 found a 26 per cent higher rate of subsequent heart failure in those treated with anthracycline cancer drugs compared with non-anthracycline drugs. Anthracyclines are a class of drugs used on a variety of cancers and still are a mainstay in breast cancer treatment. The research was published in the Journal of Clinical Oncology .
Although anthracycline drugs are of more concern, most of the drugs used to treat breast cancer pose some short-term and long-term potential for heart complications, doctors say.
In March, a study in the Journal of the National Cancer Institute raised concerns about radiation therapy.
The study noted that doctors have modified radiation therapy since the 1970s so that it is less harmful to the heart. However, it still can have an adverse effect on the heart, according to the study.
The study involved 1979 women who underwent radiation therapy of the internal mammary chain lymph nodes. They had higher rates of heart failure and heart valve dysfunction than those who received only breast irradiation. And women who received radiation therapy and who smoked were three times more likely to have a heart attack.
At some hospitals, oncologists now are using non-anthracycline drugs in selected breast cancer patients who already have heart problems that might be worsened by the drugs.
John Charlson, an oncologist at Froedtert, pointed to recent preliminary research suggesting that another class of cancer drugs called taxanes might be less toxic to the heart than anthracyclines. As a result of that research, about 10 per cent of breast cancer patients at Froedtert were now treated with the new drugs while doctors waited for more research to see if the drugs could be used in larger groups of breast cancer patients, he said.
Already, some internet-savvy patients were asking about other drug options because of concerns about heart damage, he said.
The other good news was that by lifestyle changes and controlling other cardiovascular risk factors, cancer patients might be able to reduce their heart risk significantly, said Pamela Douglas, co-author of the paper last month in the JournaloftheAmericanCollege of Cardiology .
That included maintaining a healthy weight, exercising and being vigilant about controlling their blood pressure and cholesterol, said Douglas, a professor of cardiology at Duke University Medical Center in Durham, North Carolina. Indeed, she said the success of breast cancer treatment means doctors increasingly are telling patients two things: ‘‘ Congratulations, you’ve been cured of cancer. Since you’ve been given a second chance at life, here’s what you need to do to optimise it.’’
In addition to radiation therapy and anthracycline drugs, the journal article noted other heart concerns associated with breast cancer treatment.
Another common breast cancer drug, Herceptin, is associated with a 2 per cent to 4.1 per cent increased incidence of heart failure.
Although endocrine therapy drugs such as tamoxifen are not known to be damaging to the heart (and might actually be beneficial for the heart), those drugs cause a small increase in formation of clots.
Promising new drugs that interfere with the blood supply to tumours might also increase the risk of clots, reduce the pumping ability of the heart and worsen high blood pressure.
At the same time, physical inactivity and weight gain can worsen heart problems for cancer patients. Some research indicates that breast cancer patients decrease their physical activity by two hours a week. Another study found that more than 70 per cent of patients increased their body weight by 2kg to 6kg.
It’s not just breast cancer patients who are at risk.
In 1999, Sue Northey underwent extensive radiation therapy for Hodgkin’s disease, treatment that would damage her heart a few years later.
Northey, 49, said she didn’t remember being told about the potential for heart problems, although things were such a blur and she was so worried about the cancer that any warnings might have slipped her mind.
‘‘ How would I have made a different decision?’’ she added. ‘‘ It was choosing between life and death, and I chose life.’’
Her cancer has been in complete remission since 1999, but a few years ago the first signs of other problems started cropping up. She began feeling short of breath in 2004. ‘‘ By the end I couldn’t even walk up a flight of stairs,’’ said Northey, an advertising executive. ‘‘ I just didn’t have any life any more.’’
Tests showed she had a condition known as constrictive pericarditis, a condition in which the pericardium, the sac around the heart, becomes inflamed, calcified and thick. A normal pericardium is about 1 to 3mm thick; Northey’s was between 5 and 8mm.
In July, Northey underwent a five-hour heart operation at Froedtert to remove scar tissue and part of the pericardium.
Her shortness of breath has gone away, and she easily can walk for a half-hour on the treadmill. ‘‘ I have a new lease on life,’’ she said. ‘‘ I feel the best I’ve felt in a decade.’’
Her case, though, was an example of how cancer patients should be especially vigilant about taking care of their hearts because of the problems that could occur long after treatment, said Northey’s doctor, Lee Biblo, a cardiologist at Froedtert.
‘‘ It’s like a chess game where you’re trying to stay five or 10 years ahead,’’ said Biblo, vicechairman of medicine at the Medical College.
‘‘ In women, heart disease is still the number one killer.’’ AP