Comparison Between Partial Nephrectomy and Ablation for Renal Tumor

Comparador Ativo: Partial Nephrectomy

a kind of operation for renal tumor

Procedimento: Partial Nephrectomy

The renal capsule is cut in a monopolar fashion around the tumor. After the renal artery is clamped with a bulldog clamp, cold cutting by scissors into the renal parenchymal boundary of the tumor is performed with an optimal surgical margin (a few millimeters). After retrograde injection of diluted indigo carmine, continuous suturing of the opened collecting system and transection of the major vessels is performed with intracorporeal knot-tying. Parenchymal suturing is performed in a continuous fashion. The 20-30 cm length of thread is used, and a knot is made at the end of the thread. A large Hem-o-lok polymer clip (Weck Closure System, Research Triangle Park, NC) is attached on the proximal side of the knot. Before the thread is tightened or cinched, the parenchyma is sutured in a running fashion with three or four stitches without any bolster so that the renal bed is kept in its natural position during the suturing.

Experimental: microwave ablation

a kind of minimally invasive therapy by using microwave device for renal tumors

Procedimento: microwave ablation

Microwave ablation is a technique that uses thermal therapy to induce complete necrosis of tumor in situ by using microwave ablation device.Antenna in the microwave ablation device was percutaneously inserted into the tumor and placed at designated place under US guidance. For tumors less than 1.5 cm, one antenna was inserted and for tumors measuring 1.5 cm or greater, two antennae were inserted in parallel with an inter-antenna distance of 1.0-2.5 cm, which were used simultaneously during MWA to obtain larger ablation zone. A 20G thermocouple was inserted about 0.5-1 cm away from the tumor for real-time temperature monitoring during MWA. MW emission didn't stop until the heat-generated hyperechoic water vapor completely encompassed the entire tumor and the measured temperature reached 60°C or remained above 54°C for at least three minutes.

overall survival

using log-rank test

local tumor progress(new lesion found adjacent to ablation zone)

using log-rank test

rate of intrarenal metastasis(new lesion found in the treated kidney, but not adjacent to ablation zone)

using log-rank test

rate of extrarenal metastasis(new lesion found outside of treated kidney)

using log-rank test

number of patients with side-effect and major complications

using chi-square test