Heart Cancer

Why do you never hear about heart cancer? Every other organ in the body, including the skin, can be afflicted by malignant tumors -- why not the heart?

I posed this question at breakfast this morning to some pals who are extremely bright and knowledgeable about many things, but not one had a clue about this. (Nor did I!) We all admitted it was an intriguing question, and perhaps a steppingstone to understanding why other organs DO get cancer. We all agreed that plenty of doctors and scientists must have pondered this, at much greater depth, and I'm sure that when everyone got back to their computers they Googled "heart cancer," as I just did.

And here's what I found:

The Mayo Clinic says heart cancer does exist, but is extremely rare:

Although heart tumors do occur, the vast majority are noncancerous (benign). A 20-year review of 12,487 consecutive autopsies in Hong Kong identified only seven cases of cardiac tumor — an incidence of less than 0.1 percent — most of which were benign.

A scientist on a Dept. of Energy bulletin board takes a stab at explaining why heart cancer is rare:

Cancer of the heart muscle called angiosarcoma do occur but are rare and occur more often in children and more often in the right side of the heart. Cancers like melanoma are known to spread to the heart. That being said, it is somewhat curious why certain tissues are less susceptible to cancer.This is typically ascribed to the belief that the more cells that are actively dividing in an organ or tissue the [more likely]* that organ or tissue will have a cancer arise in it. So skin, intestine and bone marrow which have high populations of dividing cells are more often to have a cancer arise in their cells than the heart whose muscle tissue is essentially non-dividing.

*(The citation says "less likely" but obviously means the opposite!)

And this from University of Pennsylvania's OncoLink:

Unfortunately, just like almost all the other tissues and organs, malignant tumors do occur in the heart. In addition, malignant tumors can spread to the heart from other sites (metastasis). Metastatic tumors to the heart are more prevalent than primary cardiac tumors, and the incidence is increasing as antineoplastic treatment results in longer survival .

Primary malignant tumors of the lining of the heart (pericardium) are exceedingly rare. However, tumors of the heart muscle do sometimes develop. Sarcomas are by far the most prevalent malignant tumors of the heart muscles (myocardium), angiosarcoma being the most common. Other malignant cardiac tumors that have been reported in the literature include rhabdomyosarcomas, mesotheliomas, fibrosarcomas, malignant fibrous histiocytomas, and lymphomas. Establishing the diagnosis of a cardiac malignancy is sometimes difficult because of their nonspecific clinical presentation. Surgery is the treatment of choice for most primary malignant cardiac tumors. Because the resection is often incomplete due to the extent and invasiveness of the tumor, radiation therapy can be used in conjunction with surgical resection. In general, the prognosis of a cardiac malignant tumor is poor.

So now you know! But now I wonder what other organs and tissues have low cancer rates, and why.