Some cancer patients experience heart problems due to their cancer treatment, and cardio-oncology can be exacerbated if the patient has a pre-existing heart condition.

Effect of cancer treatment on the heart

Currently, only some cancer treatments have a direct correlation with the function of the heart. While some have an immediate effect, others may not cause problems until years later.

The effects of cancer treatments on the heart can vary from patient to patient. It is dependent on several factors such as:

  • treatment and dosage
  • patient’s age at the time of treatment
  • existing risk factors such as being overweight or smoking
  • if the patient has an existing heart condition
  • if the patient has more than one type of cancer or whether they have had previous cancer treatments.


Radiotherapy treatments have only been shown to affect the heart if it is in the region that is being treated. This may include radiotherapy given to treat left-sided breast cancer if the treatment was more than 10 years ago.

Nevertheless, the advances in modern medicine mean that radiotherapy treatments for breast cancer these days are highly unlikely to cause significant heart problems. Equally, only a few chemotherapy drugs may affect the heart. The oncologist should be able to advise the patient if the prescribed drugs are likely to cause any cardiac issues.

Chemotherapy drugs

Anthracyclines are the most common drugs to affect the heart. They can damage the heart muscle and make it weaker, but most people tend not to develop any heart problems.

It is important that doctors keep an eye on the patients’ heart changes caused by anthracyclines so that they can treat them at an early stage and stop further damage.

These drugs are predominantly used in the treatment of some childhood cancers, breast cancer, soft tissue sarcomas, leukaemia and lymphomas.

Other targeted therapies and hormonal therapies have been found to have some incidence of increased heart risk.

Heart health and cancer treatment booklet

A new patient-facing booklet has been produced by Macmillian Cancer Support and the British Heart Foundation with the support of Dr Alexander Lyon, honorary consultant cardiologist at Royal Brompton and Harefield hospitals. 

The booklet equips patients with a better understanding of the functions of the heart, raises awareness of cancer treatments which can cause heart problems, and how problems can be monitored and managed by the medical team.

Visit the Macmillan website to download or order a copy.


Dr Alexander Lyon

Honorary consultant cardiologist