Objective measures of renal mass anatomic complexity predict rates of major complications following partial nephrectomy

Background: The association between tumor complexity and postoperative complications after partial nephrectomy (PN) has not been well characterized.

Objective: We evaluated whether increasing renal tumor complexity, quantitated by nephrometry score (NS), is associated with increased complication rates following PN using the Clavien-Dindo classification system (CCS).

Design, setting, and participants: We queried our prospectively maintained kidney cancer database for patients undergoing PN from 2007 to 2010 for whom NS was available.

Interventions: All patients underwent PN.

Measurements: Tumors were categorized into low- (NS: 4-6), moderate- (NS: 7-9), and high-complexity (NS: 10-12) lesions. Complication rates within 30 d were graded (CCS: I-5), stratified as minor (CCS: I or 2) or major (CCS: 3-5), and compared between groups.

Results and limitations: A total of 390 patients (mean age: 58.0 ± 11.9 yr; 66.9% male) undergoing PN (44.6% open, 55.4% robotic) for low- (28%), moderate- (55.6%), and high-complexity (16.4%) tumors (mean tumor size: 3.74 ± 2.4 cm; median: 3.2 cm) from 2007 to 2010 were identified. Tumor size, estimated blood loss, and ischemia time all significantly differed (p<0.0001) between groups; patient age, body mass index (BMI), and operative time were comparable. When stratified by CCS, minor and major complication rates for all patients were 26.7% and 11.5%, respectively. Minor complication rates were comparable (26.6 vs. 24.9 vs 32.8%; p=0.45), whereas major complication rates differed (6.4 vs. 11.1 vs. 21.9%; p=0.009) among tumor complexity groups. Controlling for age, gender, BMI, type of surgical approach, operative duration, and tumor complexity, prolonged operative time (odds ratio [OR]: 1.01; confidence interval [CI], 1.0-1.02) and high tumor complexity (OR: 5.4; CI, 1.2-24.2) were associated with the postoperative development of a major complication. Lack of external validation is a limitation of this study.

Conclusions: Increasing tumor complexity is associated with the development of major complications after PN. This association should be validated externally and integrated into the decision-making process when counseling patients with complex renal tumors.