In view of Heart Awareness Month, Dr Anupa Patel speaks about cardiac-related issues due to cancer therapies and what can be done in terms of early monitoring.
In the past 20 to 30 years, there have been significant advances in the diagnosis and treatment of cancers. Life expectancy has increased and with it, the complications related to various cancer therapies have increasingly emerged.
Cardiac-related complications can be devastating and can occur during, shortly after, or even years after treatment. Cardio-oncology, a relatively new branch of medicine, attempts to balance anti-cancer treatment and its cardiovascular risks, to optimise management of patients on an individual basis.
Broadly speaking, anti-cancer therapies can be subdivided into radiation therapy and chemotherapy.
Radiation therapy uses high-energy radiation to kill cancer cells, targeted to specific areas where tumours arise. When used for the chest and neck, due to the radiation affecting other tissues in the targeted area, it can cause complications.
This includes injury to vessels leading to atherosclerosis (plaque build-up inside arteries) and coronary artery disease (blockage of arteries that supply blood to the heart), as well as structural heart complications, leading to thickening and scarring of heart valves, muscle, and pericardium. This can affect heart muscle function. Often these complications manifest many years after radiation.
Chemotherapy uses chemical substances to target and kill cancer cells. It can cause cardiac disease through a variety of mechanisms, including direct and indirect injury to the heart muscle; inflammatory changes; rhythm disturbances; clot development; metabolic effects such as kidney disease or hypertension that increase cardiac risk; as well as acute infusion-related reactions.
These can be mitigated, if recognised early by altering the chemotherapeutic dose; type of administration; use of other medications; or by changing the chemotherapeutic drug.
However, recognition is often difficult since many symptoms of cardiac disease are shared with the underlying cancer process, or may be side effects of the drugs used. Also, patients’ responses to the same doses or drug may be vastly different; this too increases the difficulty in making the diagnosis.
Patients are often sent to a cardiologist prior to, or on commencing chemotherapy to assess their underlying cardiac risk, especially when drugs are used that may have a higher risk of causing cardiac disease.
Certain factors may identify a patient as high-risk. These are age; previous cardiovascular disease; metabolic abnormalities (hypertension, hyperlipidaemia, diabetes, obesity or kidney disease); known hypersensitivity reactions; or prior radiation or chemotherapy.
Research in cardio-oncology has allowed earlier detection of cardiac effects, primarily with the use of blood tests of heart enzymes and advanced echocardiographic imaging of heart muscle motion, called strain imaging. This has allowed the clinician to be able to identify early changes in heart muscle before the development of heart muscle dysfunction.
Cardiologists trained in strain imaging can easily and quickly assess the heart non-invasively, in their consulting rooms. Other modalities – nuclear scans, cardiac MRI and biopsies of the heart muscle – are available if the diagnosis is uncertain. However, these may require hospital admission.
Heart rhythm disturbances can be assessed with an electrocardiogram (ECG) or Holter ECG (24 or 48-hour ECG monitoring). Newer devices are also available that allow monitoring for longer periods – up to two years.
Recently, advances have been made when looking at the genetic basis of disease and using specific genetic markers to individualise therapy and avoid complications. In the future, this may radically change how we practice and offer truly personalised medicine.
Close collaboration between oncologist, cardiologist and patient is required to assess the need to alter cancer treatment, bearing in mind the risks of potential poorer anti-cancer management vs. the cardiac risk of continuing treatment. Whether or not cardiac changes occur during treatment, patients may often require long-term cardiac follow-up.
The field of cardio-oncology is dynamic and evolving, and highlights the need for a team approach to provide individualised care in cancer management.
MEET OUR EXPERT – Dr Anupa Patel
Dr Anupa Patel is a cardiologist practicing at Life Flora Clinic. She has training and experience in advanced cardiac imaging, including cardiac CT imaging and has a special interest in structural heart disease.