Prospective study of safety margins in partial nephrectomy: intraoperative assessment and contribution of frozen section analysis

To evaluate prospectively a healthy parenchymal safety margin during conservative surgery for renal cell carcinoma.

From 1997 to 2001, elective nephron-sparing surgery was performed through a flank incision in 61 consecutive patients (mean age 59.4 years, range 34.2 to 78.5). The mean tumor size was 32 mm (range 12 to 50). The tumor localization was juxtahilar in 10 and distant in 51. Prospective margin assessment used the following protocol. Margins were evaluated macroscopically by the surgeon, controlled by frozen section analysis, and subsequently measured during histologic examination. All patients were monitored with computed tomography scans, with a mean follow-up of 72.5 months (range 46 to 95).

The histologic type was clear cell in 42 patients, papillary in 17, and chromophobic cell in 2. Of the 61 patients, 57 had 1997 TNM Stage pT1 and 4 had Stage pT2. The Furhman grade was grade 1 in 16, grade 2 in 35, and grade 3 in 10. No tumor margin was positive. Frozen section analysis and routine histologic examination yielded 53 complete and 8 incomplete margins compared with 51 and 10, respectively, as assessed by the surgeons. The mean peritumoral margin was 7 mm (range 4 to 10) for the cortex and 2 mm (range 0 to 5) for the deep part. No patient developed locoregional or metastatic relapse.

No apparent relationship was observed between peritumoral margin width and the risk of disease progression, even for tumors abutting the hilum, rendering illusory a safety margin greater than 1 cm. Although the surgeons' macroscopic margin evaluations were accurate, frozen section analysis is mandatory when the margin status is in doubt. In all cases, margin negativity remains an oncologic imperative.