Heart Problems After Chemotherapy or Radiation

Some cancer treatments damage the heart. The damage can start during treatment. It can also start months or years after the last dose. The National Cancer Institute says that certain cancer drugs and radiation to the chest may cause heart problems that do not show up until years after treatment.

So you need three facts. Which drugs did you get? What total dose? Where was the radiation aimed? Those facts guide the rest of your care.

Contact your cancer team the same day if you have:

• Shortness of breath, above all when lying flat.
• New swelling of the hands, feet, ankles, or lower legs.
• Weight gain of more than 5 pounds (about 2.3 kilograms) in 24 hours.
• A heartbeat that is fast, irregular, or pounding.
• Dizziness, or a blackout.

Call 911 for chest pain, fainting, or severe breathlessness. Call 911 too for sudden numbness or weakness on one side of the body, which can be a sign of stroke. Do not wait for a clinic call-back and do not drive yourself.

The same-day list comes from the MedlinePlus drug pages for doxorubicin and trastuzumab, which say to call your doctor immediately if you notice them. Fast weight gain and swelling are not vague. They mean fluid is building up. The heart is not clearing it.

Anthracyclines are the drug class most linked to heart muscle damage. The National Cancer Institute names four: doxorubicin, daunorubicin, idarubicin, and epirubicin. Mitoxantrone is a related drug. It carries similar risk.

MedlinePlus warns that doxorubicin may cause serious or life-threatening heart problems. This can happen at any time during treatment. It can also happen months to years after treatment ends. That is why survivors need long-term heart checks.

The main injury is a weakened heart muscle. Doctors call this cardiomyopathy. If the weak muscle cannot pump enough blood, that is heart failure. The National Cancer Institute lists its signs as shortness of breath, dizziness, and swollen hands or feet.

Tests are done before doxorubicin starts. They show whether your heart can safely take the drug. MedlinePlus names two. One is an electrocardiogram (ECG), which records the electrical activity of the heart. The other is an echocardiogram, an ultrasound that measures how well the heart pumps blood. Both are repeated during treatment.

Tell the team before the first dose if you have ever had heart disease, a heart attack, or radiation to the chest.

Trastuzumab treats HER2-positive breast cancer. MedlinePlus says it may cause serious or life-threatening heart problems. Heart tests are done before and during treatment.

There is one key difference from anthracyclines. With trastuzumab, the damage is usually temporary. It often improves once the drug is stopped. But it can lead to heart failure in some people.

Heart function is checked with an echocardiogram (ECHO) or a MUGA scan. Both are done before treatment and repeated during it.

The risk is higher when HER2 drugs are given with chemo that also harms the heart. Doxorubicin (Adriamycin) and epirubicin (Ellence) are the two named. If your plan has both, ask how the monitoring accounts for that.

Radiation aimed at the chest can reach the heart. So can radiation to the left breast. The National Cancer Institute also lists radiation to the spine, neck, and kidneys. Total-body irradiation counts too.

Radiation can inflame the sac around the heart. That is called pericarditis. The risk rises with doses above 30 Gy to the cardiac window. It happens most often after radiation to the middle of the chest. Hodgkin lymphoma and breast cancer are the usual settings. Doxorubicin and cyclophosphamide have also been linked to sudden pericarditis with fluid around the heart.

Radiation can stiffen heart valves. It can scar the arteries that feed the heart. It can also trigger rhythm problems.

The National Cancer Institute also names trastuzumab and cyclophosphamide among the drugs that tend to cause heart problems. The American Cancer Society adds cisplatin, immune checkpoint inhibitors, VEGF inhibitors, and hormone therapy including androgen deprivation therapy. Treatment can also raise blood pressure and cholesterol. Both feed long-term heart risk.

Here is the National Cancer Institute's list for childhood cancer survivors:

• Abnormal heartbeat.
• Weakened heart muscle.
• Inflamed heart, or inflamed sac around the heart.
• Damaged heart valves.
• Coronary artery disease, in which the small vessels that feed the heart narrow.
• Heart failure.
• High blood pressure.
• Blood clots and stroke.

Heart failure has no cure. But treatment helps people live longer with fewer symptoms. It uses medicines, less salt and fluid, and care of other conditions.

Ejection fraction (EF). This is the share of blood the heart pushes out with each beat. It is the number most used to track drug damage. Your own trend matters more than a single reading. Ask for the number each time. Do not settle for "it was normal."

Echocardiogram. An ultrasound of the heart. It measures ejection fraction. It also shows the valves and the sac around the heart.

MUGA scan. A nuclear scan that also measures ejection fraction. It is sometimes used in place of an echocardiogram.

Electrocardiogram (ECG or EKG). This records the heart's electrical activity. It finds rhythm problems.

MRI and CT. Used when more detail is needed.

Lipid profile. A blood test for cholesterol, because treatment can push lipids up.

A baseline test before treatment is the most useful test you will ever have. Without it, no one can tell if a later number is new.

• Ask for a written treatment summary. It should list every anthracycline, the total dose, and the radiation fields and doses.
• Ask what your baseline ejection fraction was. Then ask what it is now.
• Ask how long heart monitoring should continue after treatment. Ask who orders it.
• Ask whether you should see a cardio-oncologist. That is a heart doctor who focuses on people with cancer.
• Give the treatment summary to every new doctor. Include your primary care clinician. Late effects usually turn up outside the cancer center.

Risk rises with smoking. It rises with high blood pressure too. Blood pressure, cholesterol, diabetes, weight, and exercise can all be changed. All of them matter more in a heart that has been treated. Ask the team what exercise is safe for you. Ask for help to quit if you smoke.

• Late Effects of Cancer Treatment — National Cancer Institute
• Late Effects of Treatment for Childhood Cancer (PDQ) Patient Version — National Cancer Institute
• Cardiopulmonary Syndromes (PDQ) Health Professional Version — National Cancer Institute
• Doxorubicin Injection — MedlinePlus, National Library of Medicine
• Trastuzumab Injection — MedlinePlus, National Library of Medicine
• Heart Failure — MedlinePlus, National Library of Medicine
• Targeted Drug Therapy for Breast Cancer — American Cancer Society
• Can Chemo and Other Cancer Treatments Cause Heart Problems? — American Cancer Society
• Long-term and Late Effects of Cancer — American Cancer Society