Cardiac tumors are generally considered rare, happening in only one in 500 cardiac surgery cases. These growths are often benign and occur on the non-cardiac soft tissues surrounding. Much less likely, they may occur in the heart tissue itself. In fact, in a 17-year retroactive study, 210 of 24,614 tumors were found to be primary cardiac sarcomas. Instances where these tumors are discovered may occur only once over the career of a cardiologist.
It is more likely that cancers affecting the heart have come from elsewhere in the body. The European Society of Cardiology estimates that while remaining rare, this may occur as much as 40 times more often than true cancers of the heart. This sometimes happens when a cancer is spread to the heart via the bloodstream.
It is also possible that a nearby cancer may grow into the area. Additionally, some tumors are known to produce hormones that can damage the heart valves. Even some drugs for the treatment of cancer may pose further risk to the heart.
When these growths do occur, they affect the patient in a few ways. Chest pain or pressure, cough, fatigue, shortness of breath, swelling in the feet or ankles, and weakness are commonly reported.
These symptoms may be difficult to diagnose as they can each be attributed to a wide variety of conditions. When cancer in the heart is present, it is unlikely to be diagnosed for many years, if at all.
Doctors are still unsure what causes heart cancer though some risk factors are known. These factors include age, heredity, genetic cancer syndromes, and a damaged immune system.
Diagnosis of heart cancer includes echocardiograms, CT scans, and MRIs. Detailed images of the tumor can help a provider differentiate between benign and malignant tumors, as well as tumor identify type.
While benign tumors can sometimes be followed-up with yearly exams, larger tumors may require surgery, even if benign. Because these tumors are unlikely to be diagnosed, particularly early on, malignant tumors may not be found until surgical removal is no longer possible.
Outlook for persons with primary heart cancer is poor. Thankfully this condition remains rare.
The above video from SciShow goes into detail about why heart cancer is so unlikely.