Impact of tumor size on the clinical outcomes of patients with Robson State I renal cell carcinoma.

Background: In the TNM classification of renal cell carcinoma released in 1997, T1 tumors were defined as organ-confined tumors 7.0 cm or less in size, and T2 as those larger than 7.0 cm. The consideration of tumor size should be predicated on its prognostic value in predicting survival, because the goal of clinical staging is to separate patients into similar classes of survival based on the extent of disease at presentation. The authors examined the impact of tumor size on the clinical outcomes of patients with Robson Stage I disease to determine a size cutoff that would maximize the predictive value of the TNM staging system.
Methods: Between 1962 and 1995, 382 patients with renal cell carcinoma were treated at the Department of Urology at the Osaka Medical Center for Cancer and Cardiovascular Diseases in Osaka, Japan, and the TNM staging of 350 of those patients was recorded. Of 350 patients, 157 (45%) were at TNM Stage I, 47 (13%) at Stage II, 65 (19%) at Stage III, and 81 (23%) at Stage IV, according to the TNM stages defined in 1997. Robson Stage I includes TNM Stages I and II, and 204 patients in these stages were analyzed in this study. This study group included 146 men and 58 women with a mean age of 57.8 years (range, 26-84 years). The mean follow-up period was 5.4 years.
Results: The patient survival periods were not significantly different for those with TNM Stages I and II. This finding indicated that the tumor size cutoff of 7.0 cm was not useful in predicting the prognosis. The patients at TNM Stages I and II were then divided into two groups at each size cutoff, from 2.5 cm to 9.0 cm, at 0.5-cm intervals. The tumor size cutoff of 5.5 cm was most predictive of patient survival (P = 0.0121). None of other patient characteristics varied significantly between the two groups at this dichotomous point. Tumor size and microscopic intrarenal venous invasion, but not grade or infiltration pattern, were found in univariate and multivariate analyses to be significantly predictive of the survival of Robson Stage I patients after radical nephrectomy.
Conclusions: The current data indicate that the tumor size cutoff of 5.5 cm was most significantly predictive of the survival of Robson Stage I patients after radical nephrectomy. The tumor size cutoff of 5.5 cm was also shown to be significant in univariate and multivariate analyses.