The long-term stability of radiofrequency ablation as a monotherapy for small (< 4 cm diameter) renal-cell carcinoma was assessed in a 6-year prospective trial of 63 patients (51% male) with 112 kidney tumors. The patients were treated with percutaneous (74) or laparoscopic (38) radiofrequency ablation between November 1999 and March 2005. Sixty-one of the 63 patients were still alive as of this report; the mean follow-up was 31 months.

In this study, virtually all patients with small kidney cancers were entered into the trial, regardless of where the tumor was located in the kidney, noted Deborah Gervais, MD, director of abdominal and interventional radiology, Massachusetts General Hospital and assistant professor of radiology, Harvard Medical School, Boston, Massachusetts, United States.

The goal was to remove the cancer, she added, but not to seek wide margins, so that kidney function could be preserved as much as possible and the patient would not need dialysis. Failure of radiofrequency ablation was considered removal of the kidney.

During the follow-up period, there were 15 cases in which tumors recurred. It was noted that treatment was changed from a 50-watt probe to a 200-watt probe during the study, and nearly all of the recurring tumors occurred with the low-wattage ablation devices. Only 3 of 99 cases recurred when doctors used a more potent 200-watt device. There were 2 major complications, with ureter strictures occurring in laparoscopic procedures.

All but 1 of the 63 patients had hereditary forms of kidney cancer, and their condition was monitored for approximately 1 year prior to treatment. Kidney function was monitored before and after the procedure, with special attention pain to creatinine clearances.

The average creatinine clearance before the surgery was 110; following treatment the average creatinine clearance was 100, demonstrating little change in kidney function. "This study was remarkable," said Dr. Gervais, "in that the researchers were able to get creatinine clearances in so many of the patients."

Thirty-one patients in this study had a single tumor that was handled in one procedure, while 15 patients had 2 lesions ablated in 1 session, and 5 patients had 3 lesions ablated in 1 session. Thirty-two patients had more than 1 treatment -- often to ablate additional tumors. The average size of the tumors was 1.62 cm (0.7 cm to 3.9 cm). Of the 112 tumors ablated, 70 had medullary or central components.

Dr. Gervais said this study indicates the success of radiofrequency ablation, "but we still don't have that 5-year median survival we need to compare this procedure to surgery."

She added that, in her experience, patients who undergo radiofrequency ablation for kidney cancer do not die of that disease, but rather from comorbidity.


[Presentation title: Radiofrequency Ablation of Small < 4 cm Hereditary or Familial Kidney tumors: Long Term Results. Abstract 72]

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