Can cancer affect the heart?

Can cancer affect the heart?

Primary malignant tumours (cancer) of the heart are very rare. But the heart can be affected in cancer in more than one way. Direct involvement of cancer in the heart is usually a secondary deposit from a primary cancer elsewhere. This could be a direct spread from cancer of nearby organs or a spread through the blood stream from a distant organ (distant metastasis). During direct spread, the outer covering of the heart (pericardium) is often involved first. Other important effect of cancer on the heart is due to treatment given for the cancer. Both medications (chemotherapy) and radiation, given for treatment of cancer, can damage the heart. Hence it is very important to monitor the heart function while treating cancer.

Spread of cancer to the outer covering of the heart often presents with bleeding into the pericardial cavity. Blood collects between the outer and inner layers of the pericardium, the outer covering of the heart. If the bleeding is fast or the amount of blood collected is large, it can compress the heart and prevent proper filling. This is an emergency situation known as cardiac tamponade which has to be relieved quickly. Otherwise the person becomes very breathless and blood pressure falls, with fainting sometimes. The fluid is usually removed by aspiration under local anaesthesia (pericardial aspiration). As there is a chance for recollection, a small tube to drain ongoing collection is placed within the pericardial cavity. It is removed later when the bleeding is under control by treatment of the cancer.

Bleeding into the pericardial cavity is documented by an ultrasound scanning of the heart known as echocardiogram. It can be done in the emergency department or intensive care unit using portable equipment in an emergency. Echocardiogram can be repeated after aspiration of fluid to confirm the complete removal. Occasionally there could a residual collection in a remote region which could not be drained by aspiration and may need further treatment which could be a surgery.

Echocardiogram is also useful in finding out masses within the heart, some of which may be due to cancer. But the common tumour of the heart known as myxoma is usually not malignant (cancer). Still it can obstruct the heart valves and produce symptoms. Occasionally a small piece of the tumour may break off and get carried away by the blood circulation. It can get lodged in some important blood vessel and block it. If a blood vessel of the brain is blocked in this way, a stroke with weakness of one side of the body can occur.

Another important role of echocardiogram in cancer is evaluation prior and while on medications which are known to affect the function of the heart. Some medications may produce blocks in the blood vessels while the more common adverse effect is reduction in the pumping function of the heart. The chance increases when the cumulative dose of the medication given over a period of time is high. Chance for damage is also higher in those with pre-existing heart disease and in those who undergo radiation in addition to chemotherapy (treatment with medications).

Another important method of reducing heart muscle damage is by special formulations of the medications known as liposomal formulations. It is a nano drug delivery system using closed bilayer phospholipid vesicles (type of fats). Heart muscle damage can be reduced by using this technology. There are also medications (Dexrazoxane) which can reduce the damage to heart muscle when higher doses of anticancer medications are unavoidable.

Radiation given for cancer can affect the heart in two important ways. One is heart muscle damage producing a disease known as restrictive cardiomyopathy, in which filling of the heart is impaired. Another involvement is on the outer covering of the heart known as radiation pericarditis. Those with radiation pericarditis can develop scarring of the pericardium with thickening, a condition known as constrictive pericarditis. In that condition, gross thickening of the pericardium prevents proper filling of the heart when it relaxes after a contraction. Radiation can also cause thickening of heart valves and damage blood vessels of the heart.

So, the relation between cancer and the heart is multi-faceted. The sub specialty dealing with these aspects has been called Cardio‐Oncology/Onco‐Cardiology. That is a combination of Cardiology which deals with diseases of the heart and Oncology which deals with cancer. The cancer specialist and heart specialist work in harmony to provide optimal care for cancer. This is one situation where you cannot avoid a treatment because it has a risk of adverse effects, for obvious reasons.