title: Extreme obesity does not predict poor cancer outcomes after surgery for renal cell cancer.
abstract: To assess whether extreme obesity (body mass index [BMI] ≥ 40 kg/m(2) ) is associated with peri-operative outcomes, overall survival (OS), cancer-specific survival (CSS), or recurrence-free survival (RFS) after surgical treatment for renal cell carcinoma (RCC).
  
  
  
  After institutional review board approval, we used an institutional database to identify patients treated surgically between January 2000 and December 2014 with a pathological diagnosis of RCC. Comprehensive clinical and pathological data were reviewed. Kaplan-Meier analyses were used to estimate OS, RFS and CSS. Univariate and multivariate Cox proportional hazards analysis was used to evaluate associations with OS, CSS and RFS in patients with extreme obesity, among other known predictive variables.
  
  
  
  In all, 100 patients (11.9%) with a BMI ≥ 40 kg/m(2) and 743 patients (88.1%) with a BMI < 40 kg/m(2) who were treated surgically for RCC were identified. Morbid obesity was not associated with an increased risk of blood transfusion (odds ratio [OR] 1, 95% confidence interval [CI] 0.587-1.70; P = 1.0). The median (interquartile range) length of hospital stay (LOS) was 4 (3-6) days. Morbid obesity was not associated with longer LOS (P = 0.26) or 30-day hospital readmission rates (P = 1.0). Major complications (Clavien ≥ 3a) were recorded in 67 patients (7.95%). BMI ≥ 40 kg/m(2) was not a predictor of major complications (OR 0.58, 95% CI 0.227-1.47; P = 0.251) or 90-day mortality (P = 0.4067). BMI ≥ 40 kg/m(2) was not associated with worse OS (P = 0.7), CSS (P = 0.2) or RFS (P = 0.5). BMI ≥ 35 kg/m(2) was also not associated with worse OS, CSS or RFS (P = 0.3, 0.1, 0.5, respectively). The 5-year OS rate was 68.9% for the entire cohort, including 69 and 70% for patients with BMI < 40 kg/m(2) and BMI ≥ 40 kg/m(2) , respectively (P = 0.69). The 5-year CSS was 79.5% for the entire cohort, including 78.4 and 87.9% (P = 0.16) for patients with BMI < 40 kg/m(2) and BMI ≥ 40 kg/m(2) , respectively. The 5-year RFS rates for BMI < 40 kg/m(2) and BMI ≥ 40 kg/m(2) were 84.1 and 90.6%, respectively (P = 0.48).
  
  
  
  Extreme obesity is not associated with worse peri-operative or cancer outcomes after surgery for RCC. Surgery should remain a standard treatment option in well selected morbidly obese patients.
authors.affiliation: Department of Urology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Blute
authors.affiliation: Department of Urology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
authors.forename: Kristin
authors.initials: K
authors.lastname: Zorn
authors.affiliation: Department of Urology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Grimes
authors.affiliation: Department of Urology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
authors.forename: Fangfang
authors.initials: F
authors.lastname: Shi
authors.affiliation: Department of Urology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
authors.forename: Tracy M
authors.initials: TM
authors.lastname: Downs
authors.affiliation: Department of Urology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
authors.forename: David F
authors.initials: DF
authors.lastname: Jarrard
authors.affiliation: Department of Urology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
authors.forename: Sara L
authors.initials: SL
authors.lastname: Best
authors.affiliation: Department of Urology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
authors.forename: Kyle
authors.initials: K
authors.lastname: Richards
authors.affiliation: Department of Urology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
authors.forename: Stephen Y
authors.initials: SY
authors.lastname: Nakada
authors.affiliation: Department of Urology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
authors.forename: E Jason
authors.initials: EJ
authors.lastname: Abel
mesh_terms: D000368:Aged; D002292:Carcinoma, Renal Cell / Q000150:complications* / Q000401:mortality / Q000601:surgery*; D018572:Disease-Free Survival; D006801:Humans; D007680:Kidney Neoplasms / Q000150:complications* / Q000401:mortality / Q000601:surgery*; D008875:Middle Aged; D009767:Obesity, Morbid / Q000150:complications*; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate
keywords: class 3 obesity; morbid obesity; obesity; renal cell carcinoma