2007 Volume 98 Issue 5 Pages 671-676
(Purpose) The 1997 T staging classification for renal cell carcinoma (RCC) defined T1 as tumors measuring up to 7cm in size and T1 is subdivided into T1a and T1b with a 4cm cutoff value in the 2002 TMN classification. We evaluated the validity of these cutoff values by assessing the cancerspecific survival of patients with non-metastatic RCC according to a series of alternative size cutoff values. In addition, we calculated how these size cutoffs affected the disease specific survival rates.
(Materials and methods) A database containing the records of 200 patients with RCC who underwent open radical nephrectomy for N0M0 disease between 1985 January and 2004 January was evaluated. Tumors were stratified by cutoff values ranging from 3 to 9cm with the 1cm increments in order to evaluate whether the 7cm cutoff value is appropriate. Next, T1 RCC were stratified by cutoff values ranging from 3 to 6cm with the 1cm increment in order to verify whether the 4cm cutoff is appropriate. Lastly, tumors over 7cm diameter were stratified by cutoff values ranging from 9 to 14cm with the 1cm increments in order to verify whether the present T2-3a categories could be divided according to tumor size.
(Results) As for the T1-2 classification, a cutoff value at 7cm or 8cm shared the greatest prognostic power. Although there was no significant difference in T1a/T1b subclassification, a 4cm or 5cm cutoff value resulted in a greatest separation of survival curves for T1a and T1b. As for tumors from 9-14cm in diameter, only a 13cm cutoff value provided a significant difference in survival.
(Conclusions) Our results indicate that the present 7cm cutoff value in the TMN system is valid in terms of prognostic value. The 4cm cutoff value may not reflect the survival when total nephrectomy is considered, thus indicating that tumors at 4cm cutoff value may be valid when nephron sparing surgery is considered. The 13cm cutoff value seems to be most appropriate in N0M0 tumors with over 7cm in diameter.
