
Cancer is an abnormal growth of cells. There are actually more than one hundred known types of cancer that can happen in the human body. Cancer can manifest as a tumor, but not all cancers cause tumors and not all tumors are even cancerous; some are benign. With cancerous cell growth also comes the possibility that the growth will spread to other organs or systems in the body. This is called metastasis. In this section you can explore many of the most common forms of cancer that make people sick.