The impact of a 4 cm. cutoff point for stratification of T1N0M0 renal cellcarcinoma after radical nephrectomy

Purpose: The 1997 TNM classification defines T1 tumors as those smaller tha n 7 cm. Recently, a cutoff point of 4 cm. has been proposed to create a sub class of T1 tumors. We evaluated the validity of this cutoff point by asses sing the pathological findings and prognoses of patients with T1N0M0 renal cell carcinoma following radical nephrectomy. Materials and Methods: We reviewed the hospital charts of 333 patients with T1N0M0 tumors, followed as long as 282 months (median 63) after radical ne phrectomy. The validity of tumor size cutoff point for predicting survival outcome was tested in relation to other prognostic factors, including patie nt age, tumor position, nuclear grade, tumor histopathology and degree of m icroscopic venous invasion. Results: During followup 32 patients (9.6%) had tumor recurrence and 21 (6. 3%) died of renal cell carcinoma. A 5 cm. cutoff point maximized the differ ences in cancer specific survival rates and a 4 cm, cutoff point maximized the differences in disease-free survival rates. Tumor size was directly rel ated to microscopic venous invasion and nuclear grade, which are significan t prognostic factors, and a 4 cm. cutoff point enhanced these relationships . Conclusions: Tumor size is an important prognostic factor for patients with T1N0M0 renal cell carcinoma. A cutoff point of 4 cm. is practical for divi ding the T1N0M0 classification into T1a and T1b subclasses.