Unclassified renal cell carcinoma: an analysis of 85 cases.
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.
Karakiewicz
Pierre I
PI
Cancer Prognostics and Health Outcomes Unit, University of Montreal Health Center, Montreal, Quebec, Canada. pierre.karakiewiccz@umontreal.ca
Hutterer
Georg C
GC
Trinh
Quoc-Dien
QD
Pantuck
Allan J
AJ
Klatte
Tobias
T
Lam
John S
JS
Guille
Francois
F
de La Taille
Alexandre
A
Novara
Giacomo
G
Tostain
Jacques
J
Cindolo
Luca
L
Ficarra
Vincenzo
V
Schips
Luigi
L
Zigeuner
Richard
R
Mulders
Peter F
PF
Chautard
Denis
D
Lechevallier
Eric
E
Valeri
Antoine
A
Descotes
Jean-Luc
JL
Lang
Herve
H
Soulie
Michel
M
Ferriere
Jean-Marie
JM
Pfister
Christian
C
Mejean
Arnaud
A
Belldegrun
Arie S
AS
Patard
Jean-Jacques
JJ
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