title: Using percentage of sarcomatoid differentiation as a prognostic factor in renal cell carcinoma.
abstract: BACKGROUND
  The objective of this study was to determine if the percentage of sarcomatoid differentiation (%Sarc) in renal cell carcinoma (RCC) can be used for prognostic risk stratification, because sarcomatoid RCC (sRCC) is an aggressive variant of kidney cancer.
  
  
  METHODS
  We performed a retrospective analysis of patients who underwent surgery for RCC at our institution between 1999 and 2012. Pathology slides for all sRCC cases were reexamined by a single pathologist and %Sarc was calculated. %Sarc was analyzed as a continuous variable and as a categorical variable at cut points of 5%, 10%, and 25%. Potential prognostic factors associated with overall survival (OS) were determined using the Cox regression model. OS curves were generated using Kaplan-Meier methods and survival differences compared using the log-rank test.
  
  
  RESULTS
  One thousand three hundred seven consecutive cases of RCC were identified, of which 59 patients had sRCC (4.5%). As a continuous variable %Sarc was inversely associated with OS (P = .023). Predictors of survival on multivariable analysis included pathologic (p) T status, tumor size, clinical (c) M status and %Sarc at the 25% level. OS was most dependent on the presence of metastatic disease (4 months vs. 21.2 months; P = .001). In cM0 patients with locally advanced (≥ pT3) tumors, OS was significantly diminished in patients with > 25 %Sarc (P = .045). However, %Sarc did not influence OS in patients with cM1 disease.
  
  
  CONCLUSIONS
  Patients with sRCC have a poor overall outcome as evidenced by high rates of recurrence and death, indicating the need for more effective systemic therapies. In nonmetastatic patients, the incorporation of %Sarc in predictive nomograms might further improve risk stratification.
authors.affiliation: Department of Genitourinary Oncology, Moffitt Cancer Center, Tampa, FL.
authors.forename: Timothy
authors.initials: T
authors.lastname: Kim
authors.affiliation: Department of Genitourinary Oncology, Moffitt Cancer Center, Tampa, FL.
authors.forename: Kamran
authors.initials: K
authors.lastname: Zargar-Shoshtari
authors.affiliation: Department of Genitourinary Pathology, Moffitt Cancer Center, Tampa, FL.
authors.forename: Jasreman
authors.initials: J
authors.lastname: Dhillon
authors.affiliation: Department of Biostatistics, Moffitt Cancer Center, Tampa, FL.
authors.forename: Hui-Yi
authors.initials: HY
authors.lastname: Lin
authors.affiliation: Department of Biostatistics, Moffitt Cancer Center, Tampa, FL.
authors.forename: Binglin
authors.initials: B
authors.lastname: Yue
authors.affiliation: Department of Genitourinary Oncology, Moffitt Cancer Center, Tampa, FL.
authors.forename: Mayer
authors.initials: M
authors.lastname: Fishman
authors.affiliation: Department of Genitourinary Oncology, Moffitt Cancer Center, Tampa, FL.
authors.forename: Einar F
authors.initials: EF
authors.lastname: Sverrisson
authors.affiliation: Department of Genitourinary Oncology, Moffitt Cancer Center, Tampa, FL.
authors.forename: Philippe E
authors.initials: PE
authors.lastname: Spiess
authors.affiliation: Department of Genitourinary Oncology, Moffitt Cancer Center, Tampa, FL.
authors.forename: Shilpa
authors.initials: S
authors.lastname: Gupta
authors.affiliation: Department of Genitourinary Oncology, Moffitt Cancer Center, Tampa, FL.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Poch
authors.affiliation: Department of Genitourinary Oncology, Moffitt Cancer Center, Tampa, FL. Electronic address: wade.sexton@moffitt.org.
authors.forename: Wade J
authors.initials: WJ
authors.lastname: Sexton
mesh_terms: D000368:Aged; D002292:Carcinoma, Renal Cell / Q000401:mortality* / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000401:mortality* / Q000473:pathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012044:Regression Analysis; D012189:Retrospective Studies; D016019:Survival Analysis; D015996:Survival Rate
keywords: Histology; Kidney; Overall survival; Renal pathology; Surgery