Kidney cancer. Coloured axial computed tomography (CT) scan through the abdomen of a 59-year-old man with cancer of his left kidney (enlarged at right, pink). The cancer is nearly 9 centimetres across. It is a renal cell carcinoma, resulting in a large lesion and necrotic tissue. Cancer cells divide in an uncontrolled fashion and migrate to invade other tissues. Treatment is with surgery if the cancer is still localised, and chemotherapy and radiotherapy if it has spread.