Inside Kidney Cancer: How Tumors Grow and Spread (Metastasis). Kidney cancer progression starts when some cells in the kidney grow out of control, forming a tumor. At first, it usually stays inside the kidney and may not cause any symptoms. Over time, the tumor can grow bigger, press on nearby organs, and even enter the blood. When this happens, cancer cells can travel to other parts of the body like the lungs, bones, or liver, causing more serious problems. #KidneyCancer #RenalCellCarcinoma #Me