title: Unclassified renal cell carcinoma: an analysis of 85 cases.
abstract: OBJECTIVE
  To compare cancer-specific mortality in patients with unclassified renal cell carcinoma (URCC) vs clear cell RCC (CRCC) after nephrectomy, as URCC is a rare but very aggressive histological subtype.
  
  
  METHODS
  Eighty-five patients with URCC and 4322 with CRCC were identified within 6530 patients treated with either radical or partial nephrectomy at 18 institutions. Of 85 patients with URCC, 55 were matched with 166 of 4322 for grade, tumour size, and Tumour, Node and Metastasis stages. Kaplan-Meier and life-table analyses were used to address RCC-specific survival. Subsequently, multivariate Cox regression analyses were used to test for differences in RCC-specific survival in unmatched samples.
  
  
  RESULTS
  Of patients with URCC, 80% had Fuhrman grades III or IV, vs 37.8% for CRCC. Moreover, 36.5% of patients with URCC had pathologically confirmed nodal metastases, vs 8.6% with CRCC. Finally, 54.1% of patients with URCC had distant metastases at the time of nephrectomy, vs 16.8% with CRCC. Despite these differences in the overall analyses, after matching for tumour characteristics, the URCC-specific mortality rate was 1.6 times higher (P = 0.04) in matched analyses and 1.7 times higher (P = 0.001) in multivariate analyses.
  
  
  CONCLUSIONS
  These findings indicate that URCC presents with a higher stage and grade, and even after controlling for the stage and grade differences, predisposes patients to 1.6-1.7 times the mortality of CRCC.
authors.affiliation: Cancer Prognostics and Health Outcomes Unit, University of Montreal Health Center, Montreal, Quebec, Canada. pierre.karakiewiccz@umontreal.ca
authors.forename: Pierre I
authors.initials: PI
authors.lastname: Karakiewicz
authors.forename: Georg C
authors.initials: GC
authors.lastname: Hutterer
authors.forename: Quoc-Dien
authors.initials: QD
authors.lastname: Trinh
authors.forename: Allan J
authors.initials: AJ
authors.lastname: Pantuck
authors.forename: Tobias
authors.initials: T
authors.lastname: Klatte
authors.forename: John S
authors.initials: JS
authors.lastname: Lam
authors.forename: Francois
authors.initials: F
authors.lastname: Guille
authors.forename: Alexandre
authors.initials: A
authors.lastname: de La Taille
authors.forename: Giacomo
authors.initials: G
authors.lastname: Novara
authors.forename: Jacques
authors.initials: J
authors.lastname: Tostain
authors.forename: Luca
authors.initials: L
authors.lastname: Cindolo
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Ficarra
authors.forename: Luigi
authors.initials: L
authors.lastname: Schips
authors.forename: Richard
authors.initials: R
authors.lastname: Zigeuner
authors.forename: Peter F
authors.initials: PF
authors.lastname: Mulders
authors.forename: Denis
authors.initials: D
authors.lastname: Chautard
authors.forename: Eric
authors.initials: E
authors.lastname: Lechevallier
authors.forename: Antoine
authors.initials: A
authors.lastname: Valeri
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Descotes
authors.forename: Herve
authors.initials: H
authors.lastname: Lang
authors.forename: Michel
authors.initials: M
authors.lastname: Soulie
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Ferriere
authors.forename: Christian
authors.initials: C
authors.lastname: Pfister
authors.forename: Arnaud
authors.initials: A
authors.lastname: Mejean
authors.forename: Arie S
authors.initials: AS
authors.lastname: Belldegrun
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Patard
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D002648:Child; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D009392:Nephrectomy / Q000379:methods*; D012044:Regression Analysis; D016019:Survival Analysis