Optimal Surgical Margin in Nephron-sparing Surgery for T1b Renal Cell Carcinoma

ObjectiveTo determine the optimal surgical margins in nephron-sparing surgery (NSS) for T1b renal cell carcinomas (RCC).Materials and MethodsWe retrospectively assessed 87 T1b RCC specimens after radical nephrectomy through whole-kidney continuous sections, with 92 T1a RCCs included as controls. The completeness of pseudocapsule (PS) and extra-PS lesions and multifocality were microscopically examined, as was the greatest distance between extra-PS lesions and primary tumors.ResultsThe rates of incomplete PS (34% [30/87] vs 18% [17/92], P = .015) and positive cancer lesions beyond the PS (39% [34/87] vs 25% [23/92], P = .043) were significantly higher in the T1b than in the T1a group. All extra-PS lesions were located within 3.0 mm of the primary tumor. Multifocal tumors were found in 6% (5/87) of patients with T1b and 5% (5/92) of patients with T1a tumors (P = .928).ConclusionThese results indicate that 4 mm may be the optimal surgical margin for NSS for patients with T1b RCC because all extra-PS lesions were located within 3 mm of the primary tumors.