"Cancers are staged 1–3/4, depending on the cancer and the severity. When detected at stage 1, a person suffering from most types of cancer has about a 95% chance of surviving. The odds go down as you get to stage 3 or 4; some cancers only have 3 stages, while others have 4. Doctors will often add an A or B to the staging as well, and this can relate to whether or not the cancer has invaded other tissues. Not every change in the body’s tissues is cancer. Some tissue changes may develop into cancer if they are not treated, however. Hyperplasia occurs when cells within a tissue divide faster than normal and extra cells build up, or proliferate. However, the cells and the way the tissue is organized look normal under a microscope. Hyperplasia can be caused by several factors or conditions, including chronic irritation. Dysplasia is a more serious condition than hyperplasia. In dysplasia, there is also a buildup of extra cells, but the cells look abnormal and there are changes in how the tissue is organized. In general, the more abnormal the cells and tissue look, the greater the chance that cancer will form. Some types of dysplasia may need to be monitored or treated. An example of dysplasia is an abnormal mole, called a dysplastic nevus, that forms on the skin. A dysplastic nevus can turn into melanoma, although most do not. Normal cells may become cancer cells. Before cancer cells form in tissues of the body, the cells go through abnormal changes called hyperplasia and dysplasia. In hyperplasia, there is an increase in the number of cells in an organ or tissue that appear normal under a microscope. In dysplasia, the cells look abnormal under a microscope but are not cancer. Hyperplasia and dysplasia may or may not become cancer. There are more than 100 types of cancer. Types of cancer are usually named for the organs or tissues where the cancers form. For example, lung cancer starts in cells of the lung, and brain cancer starts in cells of the brain. Cancers also may be described by the type of cell that formed them, such as an epithelial cell or a squamous cell."