Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body.[1][2] These contrast with benign tumors, which do not spread.[8] Possible signs and symptoms include a lump, abnormal bleeding, prolonged cough, unexplained weight loss and a change in bowel movements.[3] While these symptoms may indicate cancer, they may have other causes.[1] Over 100 types of cancers affect humans.[8]