Cancer is a malignant tumor caused by epithelial tissue, which is metaplastic, so where there is epithelial tissue, there is the possibility of cancer. Epithelial tissue covers the surface of human body, lining the inner surface of digestive tract, respiratory tract, urinary tract and reproductive tract, and is also an essential component of organs such as liver, kidney, breast and prostate. So these tissues and organs are easy to become cancerous. There is no epithelial tissue in the heart, because the heart is made up of myocardium, and myocardial cells no longer divide and increase after birth, so it is difficult for myocardial cells to become cancerous. The heart and blood vessels form a closed blood circulation system, which is not easy to be directly attacked by harmful substances from outside. Many carcinogens in people's lives may cause different degrees of damage to nasopharyngeal, oral cavity, esophagus, gastrointestinal, lung, skin and other organs, and then lead to malignant lesions. Compared with these organs that are exposed to harmful substances every day, the heart hidden deep in the core of the body is less vulnerable to direct damage from these carcinogens. Even harmful substances entering the blood stream can be continuously purified when passing through the liver, spleen and kidney. In this way, some harmful substances in the blood are also difficult to have adverse effects on the heart.
In one's life, the heart beats all the time, stays up all night and never stops. The heart is a pumping station for human blood circulation. Because the blood flowing through the heart never stops, even metastatic malignant tumor cells should not stay in the heart. It's not that there is absolutely no tumor in the heart. It is reported that the incidence of cardiac angiosarcoma and malignant lymphoma in AIDS patients has increased, and the latter can even be the direct cause of death. The heart itself also has conscience tumors, such as myxoma in the heart cavity, sarcoma of rhabdomyosarcoma and metastatic tumors. It's just metaplasia, no cancer.