A Retrospective Comparison of 2 Methods of Intraoperative Margin Evaluation During Partial Nephrectomy

Purpose: Intraoperative pathological consultation is often used to achieve negative margins during partial nephrectomy. Commonly a tumor bed biopsy for frozen section is taken from the most suspicious area of the defect. Alternatively the pathologist may perform prosection of the intact partial nephrectomy specimen and prepare frozen sections of suspicious areas. We determined the sensitivity and specificity of these 2 methods and a combined method. Materials and Methods: Records of 251 cases performed at a single institution between 2005 and 2007 were retrospectively analyzed. Results: Of the patients 56% were male. Mean age was 58.8 years. Laparoscopic resection was performed in 76% of cases. Mean greatest tumor dimension was 2.9 cm. Tumor bed biopsy was done in 120 cases, of which 15 (12.5%) showed positive final margins. With permanent section as the gold standard, tumor bed biopsy was 25% sensitive (95% CI 6-46) and 100% specific (95% CI 96-100) for detecting positive margins. In contrast, gross intraoperative consultation with or without frozen section in 163 cases, including 112 with gross intraoperative consultation only and 51 with frozen section, revealed positive final margins in 16 (9.8%) and was 75% sensitive (95% CI 50-90) and 100% specific (95% CI 97-100). The combined method involving tumor bed biopsy plus gross intraoperative consultation was 100% sensitive (95% CI 60-100) and 100% specific (95% CI 89-100). Conclusions: The data support the routine practice of combined gross pathological consultation and tumor bed biopsy. When the combined method is not used, gross intraoperative consultation is more diagnostically accurate than tumor bed biopsy. The data do not support the common practice of examining the tumor bed biopsy alone.