Viability of Glomeruli and Proximity to Tumor in Partial Nephrectomy Specimens for Renal Cell Carcinoma.
Elaine T Lam, Amir Mortazavi, Gary S Phillips, David Sharp, Debra Zynger. The Ohio State University Medical Center, Columbus
Background: The optimal surgical margin size for partial nephrectomy has not been clearly defined. Current surgical technique attempts to preserve the maximum amount of non-neoplastic renal tissue although it is unknown whether closer surgical margins translate into improved preservation of renal function. Mechanical compression from the tumor may lead to glomerular injury and the kidney surrounding the tumor may not be functional. Therefore, the goal of preserving all non-neoplastic renal parenchyma with a surgical margin of nearly zero may not be necessary and could increase positive surgical margins. In this study, the viability of glomeruli adjacent to renal cell carcinoma in partial nephrectomy specimens was evaluated.
Design: We retrospectively reviewed 53 partial nephrectomy cases containing renal cell carcinoma. Tumor size and minimum/maximum resection margins were measured. Glomeruli within 0-0.25 cm, 0.25-0.5 cm, 0.5-0.75 cm, and 0.75-1.0 cm from the tumor were quantified and categorized as 1) nonviable (matrix occupying >90% of the glomerular space), 2) minimally viable (including matrix 50-90% or markedly disrupted glomeruli) and 3) viable (all other glomeruli). Spearman's rank-method was used to evaluate the correlation between tumor size and minimum/maximum margins. Random-effects linear regression was used to test the association between percent of viable glomeruli and closeness to tumor. Wilcox rank-sum method was used to compare the size of the resected margin and margin status.
Results: The mean percentages of viable glomeruli in successive 0.25 cm distances from the tumor were: 0-0.25 cm, 58%; 0.25-0.5 cm, 80%; 0.5-0.75 cm, 90%; 0.75-1.0 cm, 92%. The absolute percent of viable glomeruli was 24.4% higher in the region >0.5 cm from the tumor compared with the region ≤0.5 cm from the tumor (p= < 0.001). Median tumor size was 2.5 cm (range 0.7-8.7 cm, mean 2.9 cm) with median minimum margin of 0.15 cm (range 0-0.9 cm, mean 0.2 cm) and maximum margin of 0.7 cm (range 0.3-1.7 cm, mean 0.8 cm). There was no significant correlation between tumor size and minimum or maximum margin, tumor size and glomerular viability or margin size and incidence of positive margins.
Conclusions: Our findings demonstrate that the immediate peri-tumoral rim of non-neoplastic tissue is abnormal and populated with a mixture of nonviable, minimally viable and viable glomeruli. Distance from the tumor correlates with increased viability of glomeruli which should be considered to define the optimal surgical margin size for partial nephrectomy.
Category: Genitourinary (including renal tumors)
Wednesday, March 2, 2011 9:30 AM
Poster Session V # 125, Wednesday Morning