Minimally invasive treatment successfully destroys kidney tumors

Treatment appropriate for some patients who are not good surgical candidates

A minimally invasive, experimental treatment is proving successful in removing small kidney tumors from appropriate patients, report researchers from Massachusetts General Hospital (MGH). In a study in the February 2003 issue of Radiology, the MGH team describes how a technique called radiofrequency ablation (RFA) destroyed all renal cell carcinoma (RCC) tumors less than 3 cm in size and some larger tumors, depending on their location. The most common form of kidney cancer, RCC will be diagnosed in almost 32,000 Americans this year and is most frequently treated with surgical removal through either an open or laparoscopic procedure.

“We’re very pleased with the success we’ve had, particularly treating small tumors and those on the outside of the kidney,” says Debra Gervais, MD, of the Abdominal Imaging and Interventional Radiology Service in the MGH Department of Radiology, the paper’s first author. “We now have an another year of experience beyond what is reported in this paper – more than 30 additional patients – with similar results.”

RFA delivers heat generated by electrical energy to tumor sites through a thin needle, similar to probes used in biopsy procedures. Placement of the probe is guided by CT scan, ultrasound or other imaging techniques. Widely used to treat cardiac arrhythmias, RFA is also being investigated for destruction of small liver tumors and has been used for more than ten years to treat a benign bone tumor called osteoid osteoma. Researchers at several centers have used it for patients with kidney tumors for whom surgical removal was not an option — including patients with only one kidney — and the current study reports what may be the largest number of patients treated and the longest followup time.

The MGH researchers describe the outcomes for the first 34 consecutive patients treated with RFA over a three-and-a-half-year period. Because surgical removal cures kidney tumors, the only patients treated with RFA were those with medical conditions making surgery risky or with either a single kidney or poor kidney function. A total of 42 individual tumors were treated, ranging in size from 1 to almost 9 centimeters. All tumors located on the surface of the kidney were completely destroyed, regardless of size. Although larger tumors within the central kidney were more difficult to treat, more than half of such tumors were destroyed with additional treatments.

Patients were evaluated one, three and six months after treatment, then at six-month or one-year intervals. During the followup period, which ranged from three months to three and a half years, four patients died of unrelated causes, two of whom had no tumor recurrence. The other 30 patients have had no local recurrence of the treated tumor. None of the patients with limited kidney function needed to go on dialysis.

Peter R. Mueller, MD, MGH director of Abdominal Imaging and the paper?s senior author, says, “The team approach that we?ve taken with our colleagues in urology is a major aspect of the success we’ve had with this treatment. We’re very excited about the results we’re seeing and the very low rate of complications. Even patients with multiple tumors can be treated as outpatients and maintain good kidney function.”