External validation of the Leibovich prognosis score for nonmetastatic clear cell renal cell carcinoma at a single European center applying routine pathology.

PURPOSE: The Leibovich prognosis score was developed as a prognostic tool for metastatic disease after radical nephrectomy for clear cell renal cell carcinoma using pathology review. However, this scoring system has never been externally validated. We externally validated its prognostic accuracy using routine pathology reports.

MATERIALS AND METHODS: We retrospectively evaluated data from the routine pathology records of 1,754 consecutive patients with nonmetastatic clear cell renal cell carcinoma operated on between 1984 and 2006 at a single tertiary academic center. Clear cell renal cell carcinoma cases were categorized as 0 to 11 by the Leibovich prognosis score and further stratified into low, intermediate and high risk groups. Metastasis-free survival was assessed using the Kaplan-Meier method. To evaluate the prognostic impact a multivariate Cox regression model was used and prognostic accuracy was determined using Harrell's concordance index.

RESULTS: Median followup was 82 months (IQR 39-142). Metastasis developed in 375 of the 1,754 patients (21.4%). The 10-year metastasis-free survival rate for Leibovich scores in our study ranged from 95% for scores of 0 and 1 to 12% for scores of 8 or greater. Pathological T stage, N stage, low tumor grade, large tumor diameter and histological tumor necrosis were independent predictors of metastasis-free survival (p <0.001). Harrell's concordance index was 0.778.

CONCLUSIONS: Risk prediction by the Leibovich prognosis score using routine pathological results was comparable to that of the original data based on pathology review. Our data support using the Leibovich prognosis score in clinical practice for followup decisions and patient selection for adjuvant treatment trials.