By AMERICAN HEART ASSOCIATION NEWS
In a way, Breast Cancer Awareness Month — October — is also Cardiac Effects Awareness Month. Or at least it should be, many oncologists, cardiologists and survivors believe.
After all, when Barbara Collins received a diagnosis of stage 2 breast cancer at age 52 in July 2011, she couldn’t worry about potential heart disease risks down the road. Her life had just been threatened. Her immediate focus was to research and treat aggressively the advancing cancer cells, and next, to survive.
As mother to six daughters, she had added worry: Her second daughter was scheduled to get married that September, and Collins’s doctors recommended she start chemotherapy as soon as her surgery and radiation treatments finished.
And yet, “I didn’t want to start chemo right away, then lose my hair at her wedding, then have the wedding be ‘all’ about me and my cancer,” she said. “I wanted to keep the focus on the bride. I kept asking my doctors: ‘If I wait just eight weeks, will the chemo still ‘get’ it?’”
It would, believed her doctors in Kerrville, Texas, and at MD Anderson Cancer Center in Houston. They decided to let her wait. This was six years ago; Collins is now cancer-free.
At the same time, she now faces fresh threats and ongoing aftercare for heart-related side effects, or “cardiotoxicity,” related to her cancer treatment. Collins is being treated for sluggish ejection fraction, meaning her heart isn’t pumping out enough blood with each contraction.
In general, late effects of breast cancer treatment can result from both chemotherapy and radiation treatments. Chemo-related cardiotoxic effects include cardiomyopathy, congestive heart failure and irregular heartbeats, while radiation can damage the heart and its valves, as well as the sac encircling the heart.
These “latent effects” of breast cancer treatment are said to occur from the one-year anniversary of treatment onward, said cardiologist Jean-Bernard Durand, M.D., medical director of cardiomyopathy services at MD Anderson Cancer Center.
“The oncology world has made tremendous strides in breast cancer treatment,” Durand said. “Where I believe we have failed as a community is that people are now living long enough [after cancer] to the point they are dying of cardiac conditions related to their treatment. We need to detect these things early.”
More specifically, in regard to radiation, dose matters. A 2013 study found that the risk of heart attack, bypass surgery or death from heart disease increased by about 7 percent for every radiation unit.
For patients with right-sided breast cancer, most radiation treatments today expose the heart to one to two units. Among women with left-sided breast cancer, a slightly higher dose of radiation typically reaches the heart, although the amount varies markedly.
But the overall heart risk remains low for a treatment proven to reduce the rate of recurrences and deaths from breast cancer. For example, a 50-year-old woman who receives a tangential radiation dose to the heart of 3 units would face a 0.5 percent increased risk of dying by age 80 from ischemic heart disease, from 1.9 percent to 2.4 percent.
The targeted drug Herceptin (trastuzumab) and hormonal therapies used to treat certain types of breast cancer may also harm the heart, said Nisha Unni, M.D., an oncologist and assistant professor of internal medicine at UT Southwestern Medical Center in Dallas.
“An effort should be made to avoid or minimize the use of therapies with increased cardiac toxicity, and use established alternative treatments available that will not compromise cancer-specific outcomes,” Unni said.
“Oncologists may tell women about potential risks, but patients are getting so much information they may not remember,” said Mary Ann Bauman, M.D., a Seattle-based primary care internist and national board member for the American Heart Association. “I have a family member who just finished her radiation for breast cancer, and I don’t want to scare her about potential cardiac effects of her treatment.”
But, Bauman said, she will be warning her sister about symptoms to watch for that may signal a heart issue.
The American Society of Clinical Oncology in March released guidelines to help prevent and watch for cardiotoxic effects of cancer treatment. Durand helped write the guidelines, which recommend screening for high blood pressure, diabetes and other heart disease risk factors, as well as an echocardiogram, before starting potentially cardiotoxic cancer treatments. For patients at increased risk for heart problems, doctors should monitor them during and after cancer treatment, the guidelines say.
At the same time, oncologists and radiation oncologists point out that patients have benefited greatly from changes in radiation dosing since the 1990s, as well as advances in the technology itself.
“It is safer now than in the 1980s and ’90s in regard to the heart,” Bauman said. “There is better targeting and less [harmful] effects of ionizing radiation on the heart.”
Still, one stark fact remains: Heart disease kills more women each year than all types of cancer combined.
In Collins’s case, she had noticed having irregular heartbeats long before the cancer came along.
“I just really worried about what this was going to do to my heart,” she said of her chemotherapy and radiation treatment. “But when you’re in a fight like this, you sign the consent forms to save your life, even though it could take your life.”
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