Better treatments for breast cancer have contributed to the growing number of breast cancer survivors, now about three million in the United States. However, these women may face a heightened risk of heart disease from the cardiotoxic effects of chemotherapy and radiation, according to a statement from the American Heart Association in the Feb. 20, 2018, issue of Circulation.
Doctors have long known that certain cancer drugs can decrease the heart’s pumping ability, especially doxorubicin (Adriamycin) and trastuzumab (Herceptin), two common treatments for breast cancer. Many women receive radiation therapy as well, which can cause heart tissue to scar or stiffen, possibly leading to valve disorders, coronary artery disease, or other heart problems. But specialists who focus on keeping the heart healthy during and after cancer treatment — known as cardio-oncologists — can offer strategies to both prevent and treat heart damage from cancer therapy.
A focus on prevention
In the past, cardio-oncologists mainly treated people who developed heart-related symptoms after cancer therapy. “These days, more people are seeing cardio-oncologists before undergoing cancer treatment,” says Dr. Tomas Neilan, director of the cardio-oncology program at Harvard-affiliated Massachusetts General Hospital.
This step is similar to what doctors refer to as clearance for surgery, during which a primary care physician or cardiologist evaluates a person’s cardiovascular health before a major operation. In both cases, the goal is finding ways to minimize the patient’s risk.
As an example, Dr. Neilan recently saw a 66-year-old woman newly diagnosed with breast cancer. “I changed her blood pressure regimen to include a more effective drug that may have a secondary benefit of protecting her heart during chemotherapy,” he says. To track any possible changes to her heart, she will receive a heart ultrasound (echocardiogram or “echo”) to check for heart abnormalities before and six months after starting doxorubicin. Cancer treatment guidelines recommend that surveillance schedule for most patients taking doxorubicin and similar drugs, known as anthracyclines. About 30% of women with breast cancer receive trastuzumab; they are supposed to have an echo every three months during treatment. Early diagnosis and treatment of a weakened, damaged heart (heart failure) may improve survival.
For most breast cancer patients, the risk of developing heart failure from chemotherapy is quite low—less than 0.5% per year. Radiation therapy raises heart attack risk by approximately 1% per year and also increases the risk of heart failure. But because many women get both treatments and are surviving for one or more decades afterward, those low yearly risks add up to a higher cumulative risk, Dr. Neilan says.
What you can do
Strategies that may help are exercise, statins, and aggressive blood pressure control. “There are consistent data showing that for women with breast cancer, physical activity not only improves survival, it also decreases the risk of heart injury related to breast cancer treatment,” says Dr. Neilan. He recommends exercising for 30 to 45 minutes at least five days a week. Preliminary evidence suggests that statins (which are widely prescribed to lower heart disease risk) may help preserve heart function when taken during chemotherapy. Dr. Neilan is currently heading a clinical trial to further test this observation. In addition, aiming for the recently updated blood pressure targets, which were lowered to a goal of 130/80 millimeters of mercury or less, will also likely protect the heart during chemotherapy and radiation, he adds.
When talking with patients, his overall message is positive. “We’re piggybacking on the phenomenal success of oncologists,” he says. If you’re diagnosed with cancer, do whatever your oncologist recommends, he stresses. Whatever happens from a cardiovascular perspective can usually be addressed.
If you were treated for breast cancer (or another type of cancer) years ago, should you have an echo on a routine basis? Unfortunately, there aren’t enough data yet to offer a clear answer. Some cardio-oncologists, including Dr. Neilan, recommend an echo for certain cancer survivors after three to five years, depending on what type of treatment they received and their other heart-related risks.
All cancer survivors should stay vigilant for any new heart-related symptoms during and after treatment and report them right away to their physician. Common symptoms include shortness of breath, weakness, fatigue, or a rapid, irregular heartbeat.