Journal articles this month compare different methods for treating kidney tumors, review new minimally invasive treatments for prostate lesions, and explain new techniques.

Method comparison

Comparison of cryoablation, radiofrequency ablation and high-intensity focused ultrasound for treating small renal tumors

BJU International 2005;96(9):1224

The authors discuss the efficacy and morbidity rates of the most promising ablative technologies — cryoablation, RFA, and high-intensity focused ultrasound — for treating small renal masses and conclude that cryoablation and RFA show great promise. They find that initial reports show that cryoablation produces recurrence rates approaching, and morbidity rates significantly less than, those of laparoscopic partial nephrectomy. There are fewer results available for RFA, but the authors conclude that it may also represent a viable clinical alternative for treating small renal masses. However, they conclude that high-intensity focused ultrasound has not been shown to give adequate tumor control.

Equipment evaluation

Radiofrequency ablation for small hepatocellular carcinoma: prospective comparison of internally cooled electrode and expandable electrode

Radiology 2006;238:346-353

This Japanese study compares the effectiveness of RFA performed by using an internally cooled electrode and an expandable electrode for the treatment of small HCCs in 74 patients with 83 nodules. The study found roughly equivalent effectiveness between the two probe designs but noted higher rates of major complications with the expandable electrode. Rates of major complications were 0% for the internally cooled electrodes and 2.1% for the expandable electrode per session, and 0% and 2.8%, respectively, per patient. Overall one-, two-, and three-year survival rates were slightly higher for the internally cooled electrode: 100% versus 94%, 94% versus 92%, and 94% versus 77%, respectively.

Multipolar radiofrequency ablation of hepatic tumors: initial experience

Radiology 2005;237:1056-1062

This German team evaluates the feasibility, achieved ablation zone size and shape, technical effectiveness, and complications of RFA for hepatic tumors. Nineteen malignant liver tumors were treated with a multipolar resistance-controlled RF ablation system that permits up to three internally cooled bipolar coagulation electrodes to be operated simultaneously. Complete tumor destruction was achieved in 18 of 19 tumors. Thirteen patients were treated with a percutaneous approach and six with an intraoperative approach. Maximum ablation size was 91 by 62 by 79 mm with the percutaneous approach and 73 by 98 by 74 mm with the intraoperative approach. Of the 18 ablation zones that could be completely evaluated, 13 were concentric, two were moderately eccentric, two were eccentric, and one was wedge-shaped.

New procedures and uses

Radiofrequency ablation of metastatic mediastinal lymph nodes during cooling and temperature monitoring of the tracheal mucosa to prevent thermal tracheal damage: initial experience

Radiology 2005;237:1068-1074

This Japanese group shares its experience in treating mediastinal lymph node metastases in seven patients over a total of 10 sessions. Cooling and temperature of the tracheal mucosa were monitored in eight sessions in which RFA was used. The one-year survival rate was 60%, and the median survival time was 13 months. They conclude that RFA may be effective for local control of small metastases and that cooling and temperature monitoring of the tracheal mucosa in the proper position may prevent thermal tracheal damage.

Emerging minimally invasive techniques for treating localized prostate cancer

BJU International 2005;96(9):1230

The authors review and evaluate cryotherapy, high-intensity focused ultrasound, photodynamic therapy, microwave, and radiofrequency interstitial tumor ablation for the treatment of localized prostate cancer in terms of development, technique, mechanism of action, and results of recent trials. They contend that for these minimally invasive methods to become acceptable alternatives to more established treatments, they should have equivalent oncological outcomes and cause less morbidity than the current standard options. The authors determine that recent technological advances and technical modifications in cryotherapy provide encouraging intermediate-term outcomes with acceptable morbidity (excluding potency), particularly in men with localized prostate cancer recurrence after radiotherapy. Results for high-intensity focused ultrasound have been less impressive, but the optimization of methods and refinement of techniques are still ongoing. For both cryosurgery and focused ultrasound, longer-term data are required before final conclusions are made. Finally, the authors determine that microwave, photodynamic therapy, and RF interstitial tumor ablation, which have been studied only in animal models or small pilot studies, can induce tumor necrosis safely but are still under investigation and hence should be considered experimental at this stage.