title: Objective measures of renal mass anatomic complexity predict rates of major complications following partial nephrectomy.
abstract: 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).
  
  
  METHODS
  We queried our prospectively maintained kidney cancer database for patients undergoing PN from 2007 to 2010 for whom NS was available.
  
  
  METHODS
  All patients underwent PN.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center, Temple University School of Medicine, Philadelphia, PA 19111, USA.
authors.forename: Jay
authors.initials: J
authors.lastname: Simhan
authors.forename: Marc C
authors.initials: MC
authors.lastname: Smaldone
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Tsai
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Canter
authors.forename: Tianyu
authors.initials: T
authors.lastname: Li
authors.forename: Alexander
authors.initials: A
authors.lastname: Kutikov
authors.forename: Rosalia
authors.initials: R
authors.lastname: Viterbo
authors.forename: David Y T
authors.initials: DY
authors.lastname: Chen
authors.forename: Richard E
authors.initials: RE
authors.lastname: Greenberg
authors.forename: Robert G
authors.initials: RG
authors.lastname: Uzzo
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D007668:Kidney / Q000033:anatomy & histology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009392:Nephrectomy / Q000379:methods / Q000706:statistics & numerical data*; D011183:Postoperative Complications / Q000453:epidemiology*; D012189:Retrospective Studies; D016896:Treatment Outcome