The present study evaluated the risk of developing ischemic heart disease in patients treated with radiotherapy for breast cancer. Patients who received radiotherapy for breast cancer are at increased risk of developing ischemic heart disease in the next 20 years.

Breast cancer (BCa) is the most common type of cancer in women. BCa treatment usually involves a combination of surgery, radiotherapy and chemotherapy. Radiotherapy is generally given after surgery in order to destroy any cancer cells that may have remained after removal of the cancer, thus lowering the risk for BCa recurrence (return of the cancer). However, radiotherapy does not act only on cancer cells. Radiation therapy can have side effects on the surrounding organs and tissues such as the skin, ribs, lungs and heart. Previous studies have shown that radiotherapy for BCa increases the risk for ischemic heart disease (reduced blood supply to the heart). This can lead to angina (chest pain) and major coronary events (MCE) such as heart attacks.

This study included 2168 BCa patients who were treated with radiotherapy between 1958 and 2001. Of these, 963 women had experienced a MCE. Among these patients, 44% of MCE occurred less than 10 years after the BCa diagnosis, 33% occurred 10 to 19 years after the diagnosis and 23% occurred at 20 years or more after diagnosis. 54% of patients who experienced MCE died as a result of the cardiac event.  

Women who received radiotherapy for the left breast had a higher risk of MCE than women who were irradiated for the right breast. Also, women with a history of other circulatory problems, with diabetes, heavy smokers or women who were overweight or obese had higher rates of MCE after radiotherapy for BCa. Women who received higher doses of radiation had a greater risk of cardiac events compared to women who received lower doses of radiation. The risk of cardiac events started to increase in the first 5 years after radiation and continued for at least 20 years. 

In summary, exposure of the heart to radiation during radiotherapy for BCa increased the risk for ischemic heart disease in BCa patients. The risk for MCE increased with higher doses of radiation, began in the first 5 years after exposure and continued for the next 20 years. Patients with previous cardiac risk factors had a higher risk of ischemic heart disease.

Despite the higher risk of MCE, radiotherapy is still very important in preventing cancer recurrences.

You should make regular visits to your cardiologist to have your heart checked. Ask your doctor to advise you what changes you could make to your lifestyle to lower your risk of developing heart problems following radiation therapy.