Cancer is a class of diseases characterized by out-of-control cell growth. There are over 100 different types of cancer, and each is classified as a cell that is initially affected.
Cancer damages the body when damaged cells divide uncontrollably to form tumors or masses called tumors (except in the case of leukemia where the cancer is not the normal function of blood through the abnormal cell division in the blood). Tumors can grow and interfere with the digestive, nervous and circulatory systems, and can release hormones that alter the function of the body. Tumors that remain in one place and show limited growth are generally considered benign.
More dangerous, or malignant tumors are formed when two things happen:
1. a cancer cell is capable of moving the body through the bloodstream or lymphatic system, destroying healthy tissue in a process called invasion
2. this cell is able to divide and grow, as new blood vessels to feed in a process called angiogenesis.
When a tumor spreads to the areas of success and to grow, invade and destroy other healthy tissues, it was said metastasis. This process is called metastasis, and the result is a serious condition, which is very difficult to treat.
In 2007, cancer killed about 7.6 million people in the world. Doctors and researchers who specialize in research, diagnosis, treatment and prevention of cancer, known as oncologists.
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