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Purpose: Radio frequency ablation is an emerging nephron sparing treatment option in select patients with small renal tumors. Some have questioned the completeness of cell death and the reliability of axial imaging for radio frequency ablation followup. We present results in patients with no evidence of radiographic active disease who underwent biopsy more than 1 year following ablation. Materials and Methods: Patients who had no clinical evidence of disease, defined as absent lesion growth and contrast enhancement on computerized tomography, 1 year or more following radio frequency ablation underwent percutaneous renal biopsy to evaluate cell viability in the ablative zone. A total of 19 patients (20 lesions) were included in the study. Histological comparison of pre-ablation and post-ablation specimens was performed using hematoxylin and eosin staining. Results: Pre-ablation biopsies confirmed that 17 of 20 tumors were renal cell carcinoma, while the remaining 3 were oncocytoma. Following ablation at a mean followup of 26.9 months (range 13.1 to 58.0) all 20 lesions were stable in size without evidence of contrast enhancement on computerized tomography. At repeat biopsy all histology specimens showed unequivocal tumor eradication with no evidence of cellular viability. Histological changes beyond 1 year demonstrated coagulative necrosis, hyalinization, inflammatory cell infiltration and residual ghost cells. Conclusions: Pathological examination of radiographically negative lesions biopsied more than 1 year following radio frequency ablation confirmed no evidence of disease in all specimens. Therefore, axial imaging can reliably monitor treatment efficacy in the long term. Chronic changes after radio frequency ablation demonstrate coagulative necrosis and nonviable cells. This suggests an evolution of pathological changes that renders early post-ablative biopsy unreliable. [Copyright &y& Elsevier]

Purpose: We examined the effect of radical nephrectomy, partial nephrectomy and radio frequency ablation on renal function in patients with stage T1a renal masses. Materials and Methods: A total of 242 consecutive patients from July 1995 to March 2005 undergoing primary treatment for unilateral renal masses smaller than 4 cm and a normal contralateral kidney were identified. Renal function was calculated using the modified Modification of Diet in Renal Disease equation. The rate of decrease in the glomerular filtration rate below 60 ml per minute 1.73 m2 was compared among the 3 treatment modalities. Results: A total of 86, 85 and 71 patients were treated with radio frequency ablation, partial nephrectomy and radical nephrectomy, respectively. Preoperatively stage 3 chronic kidney disease (glomerular filtration rate less than 60 ml per minute per 1.73 m2) was identified in 65 patients (26.7%), including 26.7%, 27.1% and 26.8% who underwent radio frequency ablation, partial nephrectomy and radical nephrectomy, respectively. Following intervention the 3-year freedom from a glomerular filtration rate decrease of below 60 ml per minute per 1.73 m2 for radio frequency ablation, partial nephrectomy and radical nephrectomy was 95.2%, 70.7% and 39.9%, respectively (p <0.001). Multivariate analysis showed that radical nephrectomy was an independent risk factor vs radio frequency ablation and partial nephrectomy for stage 3 chronic kidney disease (HR 34.3, 95% CI 4.28–275 and 10.9, 95% CI 1.36–88.7, respectively). Conclusions: Decreased renal function is prevalent in patients with small unilateral renal tumors even with a normal contralateral kidney. Ablative or extirpative nephron sparing techniques are effective for preserving renal function in these patients. [Copyright &y& Elsevier]

Purpose: Nicotinamide adenine dinucleotide diaphorase staining is arguably the standard for assessing tissue viability following radio frequency ablation, yet the accuracy of this test is questionable. Thus, it is imperative to examine the reliability of nicotinamide adenine dinucleotide to predict ablation success. To evaluate the observation that immediate nicotinamide adenine dinucleotide staining may not be clinically reliable, we compared results from immediate post-ablation biopsies of renal tumors to radiological and clinical followup. Materials and Methods: Laparoscopic radio frequency ablation was performed in 9 patients and 10 tumors using a temperature modulated radio frequency system. Cold cup biopsies were taken immediately following ablation, and processed for nicotinamide adenine dinucleotide and hematoxylin and eosin staining. Patients were then followed using contrast enhanced computerized tomography at regular intervals. Results: Median tumor size was 2.3 cm. Hematoxylin and eosin stain diagnosed 8 renal cell carcinomas and 2 angiomyolipomas. A quarter of the renal cell carcinomas and both angiomyolipomas stained positive for scattered nicotinamide adenine dinucleotide diaphorase activity immediately after RFA. Mean followup for the nicotinamide adenine dinucleotide positive tumors was 28.5 months (range 24 to 30) and for the nicotinamide adenine dinucleotide negative tumors was 25 months (range 18 to 30). There was no evidence of local tumor recurrence in any patient. Conclusions: Four lesions had nicotinamide adenine dinucleotide diaphorase activity on post-ablation biopsy suggesting retained viable tissue, yet there has been no recurrence during an average 2-year followup. While negative nicotinamide adenine dinucleotide staining is consistent with nonviability, these results suggest that false-positive staining can occur immediately following RFA, making the predictive value of positive nicotinamide adenine dinucleotide diaphorase staining unclear. [Copyright &y& Elsevier]