Cancer is a group of diseases characterized by the uncontrolled growth and spread of abnormal cells. These cells can invade nearby tissues or spread to other parts of the body through the bloodstream or lymphatic system. Cancer can develop in almost any part of the body, such as the oral cavity, lungs, breast, skin, intestine, or prostate. It is a leading cause of death worldwide, but advancements in early detection, diagnosis, and treatment have significantly improved outcomes for many types of cancer.