Kidney cancer begins when some kidney cells acquire mutations in the DNA. The mutations tell the cells to grow and divide rapidly and then the abnormal cells form a tumor. If the cells break off, they will then spread or metastasize to other parts of the body. Risk factors for kidney cancer include smoking, obesity, hypertension and familial history, among others. The three main factors in aiding to reduce the risk of developing kidney cancer include quitting smoking, maintaining a healthy weight and controlling high blood pressure.