Cancer is a group of diseases characterized by the uncontrolled growth and spread of abnormal cells. If the spread is not controlled, it can result in death. Cancer can develop almost anywhere in the body and can affect people of all ages, though certain types are more common in specific age groups. The most common cancers include breast, lung, prostate, and colorectal cancer. Risk factors for cancer include genetic predisposition, lifestyle choices such as smoking and excessive alcohol consumption, exposure to harmful chemicals and radiation, certain infections, and environmental factors.