Some treatments for breast cancer can harm your heart.

And heart disease is the number one cause of death for women in the United States.

In fact, breast cancer survivors, particularly women over age 65, are more likely to die from cardiovascular disease than breast cancer, according to an American Heart Association Scientific Statement.

The statement was chaired by Dr. Laxmi Mehta, director of the Women’s Cardiovascular Health Program and an associate professor of medicine at The Ohio State University.

Mehta and her colleagues said that cardiologists and oncologists should work together when treating cancer patients, even after cancer treatment ends.

They want breast cancer patients to be aware of the potential effects of treatment on the heart.

“This should not deter or scare patients from undergoing breast cancer treatment but should allow them to make informed decisions with their doctor on the best cancer treatment for them,” Mehta said in a press release.

The full statement is published in the journal Circulation.

Treatment and cardiovascular risk

Some treatments can cause abnormal heart rhythms, weaken the heart muscle, or damage heart cells.

One of the treatments is doxorubicin (Adriamycin). However, slower administration of the drug may reduce the cardiovascular risk.

Also, a drug called dexrazoxane was recently approved for patients with metastatic breast cancer who are getting high doses of doxorubicin. It may help reduce heart cell damage, but more studies are needed to confirm this.

Dr. Paula Klein, medical director of Breast Cancer Clinical Trials at Mount Sinai Health System in New York, told Healthline that Adriamycin, also known as the “red devil,” is commonly incorporated into aggressive treatment programs.

“It is associated with irreversible toxicity. But the risk is low — less than one percent. It’s higher in older women and those with cardiovascular risk factors,” she explained.

“For those patients with early-stage HER2-positive disease, the mainstay of therapy is trastuzumab (Herceptin), which has a known cardiovascular toxicity rate of approximately one percent. But it can approach three or four percent when combined with Adriamycin,” she said.

According to Klein, there’s a group of patients whose baseline cardiac function is simply too low for Adriamycin.

“When there’s contraindication to Adriamycin, there are programs that do not use both Adriamycin and Herceptin. This program only has risk of cardiovascular toxicity of about one percent. For those patients who are young with aggressive disease we’re a little more liberal with the combination,” said Klein.

She explained that the patients at highest risk are those over age 65 and those with uncontrolled hypertension.

“One other thing to note is that the cardiovascular toxicity of Adriamycin is irreversible. And a problem can occur at any time in a woman’s life, as opposed to Herceptin toxicity, which is usually reversible. We can hold on Herceptin and usually within four to seven weeks cardiac function can return,” said Klein.

Before beginning treatment with Adriamycin and Herceptin, patients get a baseline echocardiogram and MUGA scan, she explained.

“Aromatase inhibitors are the drugs we tend to prefer in postmenopausal women over tamoxifen, due to safety and efficacy in reducing risk of recurrence. It can have a negative impact on lipid profile, which can lead to heart disease. However, this is not a prominent side effect of these medications,” said Klein.

Radiation therapy is another treatment that can cause coronary artery disease or blockages, according to the paper.

Dr. Susan Gilchrist, professor of cardiology and clinical cancer prevention at The University of Texas MD Anderson Cancer Center, told Healthline that radiation to the left side of the chest can impact the heart up to 20 years after treatment.

Shared risk factors

Aside from treatment, breast cancer and heart disease share some risk factors.

The paper noted shared risk factors that can’t be changed, such as aging and genetics.

A woman’s risk of cardiovascular disease goes up with menopause. For some women, hormone replacement therapy can raise the risks of both breast cancer and heart disease.

Lifestyle choices that increase risk, such as poor diet, physical inactivity, and smoking, can be changed.

Gilchrest cautioned that risk factors such as uncontrolled hypertension can go unchecked.

“We need to screen heart function and make sure we’re not missing something. Combining the experience from cancer treatment with unchecked risk factors can enhance cardiovascular risk,” she said.

Gilchrist explained that some breast cancer patients develop risk factors such as weight gain, loss of fitness, and high blood pressure during treatment.

Pairing oncology with cardiology

Gilchrist has researched heart health and cancer.

“We did a few studies looking at how one’s fitness impacts overall outcomes in patients with cancer. We showed that being a more fit person not only reduces the risk of cancer but the risk of cardiovascular disease and cancer mortality over time. The kind of research we did showed long-term outcomes were better when patients were more fit,” she said. “I do research, but what’s the point if you don’t put it into clinical practice?”

Gilchrist operates the first cardiovascular prevention program in the United States with total focus on improving fitness and eliminating heart health risk factors in cancer patients.

“This is important because if we keep the risk factors controlled we’re more likely to keep heart function controlled,” she said.

What people with breast cancer need to know

Breast cancer patients needn’t skip treatment or worry unnecessarily.

But they should be prepared to discuss their medical history with their oncologist.

“Know the medications you’re on so when you meet with a medical oncologist we have a clear idea what medical problems might put you at risk of inordinate toxicity. If you have special cardiovascular risks, we can tailor our chemotherapy programs to balance risk of recurrence with risk of toxicity. It’s quite important that patients are well informed about their medical health,” said Klein.

After treatment, continue to see your primary care physician.

“Certainly if you have any persistent chest pains, pressure, or palpitations, always seek care with a medical doctor, whether or not you’ve had any treatment for breast cancer,” she said.

Gilchrist added that exercise intolerance is another sign you should see your doctor. For example, if you could take a half-mile walk before treatment but can no longer do so.

“It’s important to be an active person, even during treatment. Don’t shy away from activity. And check in with your doctor to find out if your heart risk factors are in check,” she advised.

Patient engagement

“I’m hopeful as these things become more apparent we develop more rigorous ways of tracking our patients so it’s integrated into their cancer care. There’s a big push from some organizations to come up with survivorship plans to help people get on their feet without feeling they have to do it on their own,” said Gilchrist.

In her clinic, Gilchrist offers a “prescription” for exercise that includes specifics for heart rate targets as well as frequency and intensity of exercise.

“For me to guide them, I need to know the baseline of their heart and lung health. Then we focus on what to do to prevent heart problems instead of waiting until it happens and dealing with the after effects,” she said.

Her patients, said Gilchrist, are motivated and excited to have control over their health.

“I don’t just talk to them about their risks. I talk to them about their health. The last thing a cancer patient wants now is to hear they have a heart risk. I tell every woman or man in my clinic that I’m here to keep them healthy and get them back to how they were before treatment. And this is how we’re going to do it. You have control over this. It’s a positive message, not a scary one, and it’s getting people engaged in the process of keeping themselves healthy,” said Gilchrist.