pT2 classification for renal cell carcinoma. Can its accuracy be improved?
OBJECTIVE
The 2002 tumor classification for renal cell carcinoma (RCC) classifies pT2 tumors as more than 7 cm in greatest dimension, limited to the kidney. In this study we determined whether a size cutoff point exists within pT2 tumors and whether such subclassification would further improve the accuracy of the current tumor classification.


METHODS
We studied 544 patients with unilateral, sporadic pT2 RCC treated with radical nephrectomy or nephron sparing surgery between 1970 and 2000. The association of tumor size with death from RCC was examined using martingale residuals from a Cox proportional hazards regression model to determine the optimal size cutoff point.


RESULTS
There were 204 deaths from RCC a median of 3.8 years following nephrectomy. Univariately tumor size was significantly associated with death from RCC (risk ratio 1.08, 95% CI 1.04 to 1.13, p <0.001). A scatterplot of tumor size vs expected risk of death per patient suggested that a cutoff point between 9 and 10 cm was appropriate. When adjusted for regional lymph node involvement and distant metastases, the 10 cm cutoff point performed better than the 9 cm point (risk ratio 1.42, 95% CI 1.07 to 1.90, p = 0.017 vs 1.22, 95% 0.86 to 1.72, p = 0.268). Therefore, we propose using a 10 cm cutoff point to subclassify patients into pT2a and pT2b.


CONCLUSIONS
Our data suggest that the prognostic accuracy of the 2002 pT2 tumor classification can be further improved by subclassifying patients with tumors greater than 7 and less than 10 cm into a pT2a category, and those with tumors 10 cm or greater into a pT2b category.
Frank
Igor
I
Department of Urology, Mayo Medical School and Mayo Clinic, Rochester, Minnesota 55905, USA. frank.igor@mayo.edu
Blute
Michael L
ML
Leibovich
Bradley C
BC
Cheville
John C
JC
Lohse
Christine M
CM
Kwon
Eugene D
ED
Zincke
Horst
H
D002292:Carcinoma, Renal Cell / Q000145:classification* / Q000473:pathology*; D005500:Follow-Up Studies; D006801:Humans; D007680:Kidney Neoplasms / Q000145:classification* / Q000473:pathology*; D009367:Neoplasm Staging; D011379:Prognosis; D015203:Reproducibility of Results