Only a few cancers develop in the heart (see also Overview of Heart Tumors). Those that develop in the heart are called primary heart tumors. The most common primary cancerous heart tumors are sarcomas that develop from connective tissue.
Most cancerous heart tumors originate in some other part of the body—usually the lungs, breasts, kidneys, blood, or skin—and then spread (metastasize) to the heart. Metastatic heart tumors are 30 to 40 times more common than primary heart tumors but are still uncommon.
Cancers in the chest, such as lung or breast cancer, may spread to the heart by direct invasion, often into the sac that surrounds the heart (pericardium). Cancers may also spread to heart muscle and chambers through the bloodstream or through the lymph system.
The symptoms of cancerous heart tumors are essentially the same as those of noncancerous heart tumors and vary depending on the tumor's location. However, the symptoms of cancerous tumors tend to worsen more quickly than those of noncancerous tumors because cancerous tumors grow much faster.
Symptoms include sudden development of heart failure (causing shortness of breath and fatigue), abnormal heart rhythms (causing palpitations, weakness, or fainting), and bleeding and fluid accumulation into the pericardium, which may interfere with the heart's functioning and cause cardiac tamponade.
Symptoms of a metastatic heart tumor occur along with symptoms caused by the original tumor and by any metastases elsewhere in the body. For example, people who have lung cancer that has metastasized to the heart may have trouble breathing, fatigue, and coughing up of blood.
Primary cancerous heart tumors themselves may spread (metastasize) to other areas of the body. Metastases may be to the spine (causing pain), nearby tissues, or organs such as the lungs (causing trouble breathing and coughing up of blood) and brain (causing abnormal nervous system function).
The procedures used to diagnose cancerous heart tumors are the same as those used for noncancerous heart tumors, including echocardiography, computed tomography (CT), and magnetic resonance imaging (MRI).
For metastatic heart tumors, further testing is done to find the original tumor, unless its location is already known.
If tumors in the pericardium cause fluid to accumulate around the heart, that fluid may have to be drained.
Because cancerous heart tumors—both primary and metastatic—are almost always incurable, treatment is designed to reduce symptoms. Depending on the type of tumor, radiation therapy, chemotherapy, or both are used.