Cancer is a group of diseases caused by uncontrolled cell growth. The document discusses several types of cancer including breast cancer, bladder cancer, lung cancer, lymphoma, liver cancer, stomach cancer, prostate cancer, esophageal cancer, and others. It describes the risk factors, symptoms, and most common forms of each type of cancer. It also discusses how cancer cells spread, what tumor cells are, how stomach cancer is treated, and 12 types of cancer that can be inherited genetically.