Pure retroperitoneal laparoscopic radical nephrectomy and thrombectomy with delayed occlusion of the proximal inferior vena cava (DOPI) technique for renal tumor with level II-III venous tumor thrombus.

To explore the safety and effectiveness of delayed occlusion of the proximal inferior vena cava (DOPI) technique in retroperitoneal laparoscopic radical nephrectomy (LRN) and thrombectomy for renal tumor with level II-III venous tumor thrombus (VTT).