Tumors had renal sinus fat invasion (34.3%), extension beyond Gerota's fascia (17, 1%); involvements of ipsilateral renal vein (6.7%), inferior vena cava above diaphragm (4, 8%) and below diaphragm (5, 7%), invasion of ipsilateral adrenal gland (1%), local lymph nodes (13.3%) and distant metastases (5, 7%).