Does the size of the surgical margin in partial nephrectomy for renal cell cancer really matter?

Purpose: Although many groups recommend a surgical margin of 1 to 2 cm., to our knowledge the amount of normal renal parenchyma that must be excised during partial nephrectomy for stages T1-2N0M0 renal cell carcinoma to ensure a safe margin has never been critically evaluated. We investigated whether the size of the surgical margin has any effect on recurrence. Materials and Methods: All partial nephrectomies performed for localized renal cell carcinoma at our institution from 1988 to 1999 were retrospectively analyzed via a review of hospital records, pathology reports and histological slides. Parenchymal margin status was assessed and quantified by microscopy. Followup data were obtained via patient chart review and telephone interview. Average negative margin size and postoperative followup were determined, and renal cell carcinoma recurrence was assessed. Results: A total of 44 partial nephrectomies were performed with a mean followup of 49 months (range 8 to 153). Mean tumor size was 3.22 cm. (range 1.3 to 10). Surgical margins were negative for malignancy in 41 cases and positive in 3. All patients with negative margins were without local recurrence at followup except 1 with a recurrent mass adjacent to the kidney at a site distant from the original lesion. Mean and median size of the negative margins was 0.25 and 0.2 cm., respectively (range 0.05 to 0.7). In the 3 cases with positive margins there was no evidence of disease at 39 and 62 months of followup in 2, while multiple local and metastatic recurrences developed in 1. Conclusions: No patient with negative parenchymal margins after nephron sparing surgery for stages T1-2N0M0 renal cell carcinoma had local recurrence at the resection site at a mean followup of 49 months. Margin size was irrelevant. Only a minimal margin of normal renal parenchyma of less than 5 mm. must be removed during partial nephrectomy for localized renal cell carcinoma.