A comparison of the UCLA Integrated Staging System (UISS) model and the Leibovich score in survival prediction for patients with non-metastatic clear cell renal cell carcinoma


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Tiffany Tang1, Min Tun Nay1, Myo Oo Nay1, Kamalakannan Srimalan1, Caroline Choong2, Vanessa Khoo1, Valerie Khoo1, Tsung Wen Chong2, Puay Hoon Tan2, Min-Han Tan1

1The National Cancer Centre, Singapore, 2Singapore General Hospital, Singapore

Abstract

Background
Several Phase III trials of adjuvant therapy in RCC have been initiated following advances in targeted therapy. To select patients at high risk of relapse and mortality, two prognostic models the UCLA-Integrated Scoring System (UISS) model and the Leibovich score - have been incorporated into these trials. These models have not been compared previously. Our objective was to directly compare the models, including their respective trial criteria, using various survival endpoints.

Method
A retrospective study of 355 patients with unilateral non-metastatic clear cell RCC undergoing nephrectomy between 1990 and 2006 at the Singapore General Hospital was undertaken. Performance of the UISS and the Leibovich models, as well as UISS trial criteria (modified UISS trial criteria used in the ASSURE trial) and Leibovich trial criteria (used in the SORCE trial), were directly compared using log-likelihood statistics. Adequacy and concordance indices were also calculated. Study endpoints tested were overall survival (OS), cancer-specific survival (CSS) and disease-free survival (DFS).

Results
Likelihood ratio testing demonstrated a significant benefit in prediction when adding the Leibovich model to the UISS model in all outcomes tested, with no benefit using the converse approach (OS: p=0.002 vs p=0.27; CSS: p= 0.0001 vs p = 0.57; DFS: p=<0.0001 vs p=0.30). Benefit was seen primarily in disease-free survival when adding the Leibovich trial criteria to UISS trial criteria, with no benefit using the converse approach. (OS: p= 0.16 vs p=0.27; CSS: p=0.17 vs p=0.11; DFS: p=0.01 vs p=0.26).

Conclusion
Our study shows that the Leibovich model is superior to the UISS model in estimating survival outcomes in patients with non-metastatic clear cell RCC following nephrectomy. In terms of enrolment in an adjuvant trial, the Leibovich trial criteria is more useful than the UISS trial criteria in predicting high risk patients with poorer disease free survival.

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