Cancer by definition, is a deadly disease caused by an uncontrolled division of abnormal cells in a part of the body. Most common types are prostate cancer, breast cancer, colon cancer, lung cancer, lymphoma, leukemia, Melanoma (skin cancer), and Basal cell cancer. Untreated cancers can cause serious illness and death.
There are more than 100 types of cancers. The different types of cancer can behave very differently. For example, lung cancer and skin cancer are quite different diseases. They grow at different rates and respond differently to treatments.
Cancer starts when cells in a part of the body start to grow out of control. Cancer cell growth is different from normal cell growth. Instead of dying, cancer cells continue to grow and form new, abnormal cells. Cancerous cells can also invade (grow into) other tissues, something that normal cells can’t do. When a cell (or cells) grow out of control and invade other tissues, that cell is considered a cancer cell.
Note that, not all tumors are cancer. A tumor is an abnormal lump or collection of cells, but not all tumors are cancer. Tumors that aren’t cancerous are actually called benign or benign tumor.