Prognostic importance of tumor size for localized conventional (clear cell) renal cell carcinoma: assessment of TNM T1 and T2 tumor categories and comparison with other prognostic parameters.
BACKGROUND
The T1 and T2 classifications of the International Union Against Cancer TNM classification system for renal cell carcinoma are based on primary tumor size, and in various editions of the classification, the cut points between T1 and T2 have been amended to provide clinical utility. In the current edition, the T1/T2 cut point is less than or equal to and greater than 7 cm. and more recently a subdivision of the T1 classification (less than or equal to and < 4 cm) has been proposed to identify patients suitable for partial nephrectomy. This study investigates the prognostic significance of tumor size in a series of organ-confined clear cell renal cell carcinomas.


METHODS
One hundred thirty cases of organ-confined clear cell renal cell carcinomas, with a minimum of 5 years' follow-up, were identified from the New South Wales Cancer Registry. Tumor size was compared with survival using the method of Kaplan and Meier for TNM size categories, and proportional hazards regression was used for assessing size as a continuous variable. Proportional hazards regression also was used for multivariable comparisons of size and other prognostic parameters (Fuhrman grade, AgNOR score, and Ki-67 index) against survival.


RESULTS
Of 116 cases for which tumor dimension was recorded, 25 patients had died of cancer-related causes. Primary tumor size ranged from 12 to 140 mm (mean, 57.3 mm). The association between survival and size was significant irrespective of the TNM classification and was also significant when size was modeled continuously (P = 0.000125, hazard of death increased by 3.51 times for each doubling of tumor size). On univariate analysis, Fuhrman grade (P = 0.04) and AgNOR score (P = 0.015) were associated with survival; however, on multivariate analysis only tumor size retained significance.


CONCLUSIONS
Although the cut point of T1 and T2 TNM categories and the proposed T1 subdivision cut point correlate with survival, our finding that size is a continuous variable indicates that as a prognostic parameter for clear cell renal cell carcinoma, primary tumor size is relative rather than indicative.
Delahunt
Brett
B
Department of Pathology, Wellington School of Medicine, University of Otago, Wellington, New Zealand. bd@wnmeds.ac.nz
Kittelson
John M
JM
McCredie
Margaret R E
MR
Reeve
Anthony E
AE
Stewart
John H
JH
Bilous
A Michael
AM
D000328:Adult; D000368:Aged; D002292:Carcinoma, Renal Cell / Q000473:pathology*; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D019394:Ki-67 Antigen / Q000032:analysis; D007680:Kidney Neoplasms / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods*; D011379:Prognosis; D012042:Registries; D012044:Regression Analysis; D016019:Survival Analysis
D019394:Ki-67 Antigen