Why is heart cancer so rare?

That is good news: I do not know but it does occur enough to make us worry about it. Most cancers of the heart are sarcomas....but they are the worst nightmare one can be faced with. So pray that it remains rare or become even rarer!

Low carcinogens: Primary Tumors of the Heart are extremely rare in terms of those arising from the normal tissues that make up the heart. This is in contrast to secondary metastatic tumors of the heart or those that infiltrate the heart via direct extension The most common primary tumor of the heart is the benign myxoma. 20% of primary tumors of the heart are malignant and include rhabdomyosarcomas angiosarcomas and myxosarcomas. Since most are viral in origin, the high blood flow and presence of immunocytes may suppress malignant transformation