A novel prognostic model for oligometastatic renal cell carcinoma: COMPARZ study post-hoc analysis.

Abstract

e16521 Background: International metastatic renal cell carcinoma database consortium (IMDC) is the most commonly used prognostic model for metastatic renal cell carcinoma (mRCC), however, its clinical application has been limited due to the cumbersome design and vague recommendation of treatment decisions for patients in the IMDC intermediate risk group. Previous studies indicated the favorable prognosis of oligometastatic RCC, but the definition of oligometastasis has not been clarified. This study aims to construct a new prognostic model of oligometastatic RCC based on the COMPARZ study cohort. Methods: Patients from the COMPARZ study (which was a randomized phase III non-inferiority study comparing pazopanib and sunitinib in advanced RCC or mRCC patients). Patients (N=1038) were divided into two cohorts for models construction respectively, Cohort A (n=293) with primary kidney tumor; Cohort B (n=745) without primary kidney tumor. Multivariate Cox regression analysis was performed to identify the independent prognostic risk factors for each model with overall survival (OS) as primary endpoint. Uno’s C-statistics was utilized to compare the novel risk model with IMDC risk. These models were then used to examine and stratify the patients in IMDC intermediate risk group. Results: In Cohort A, four risk factors were identified independent predictors for short survival. Patients were segregated into the oligo group and the non-oligo group. The concordance index (C-index) for Model A and IMDC risk model was 0.63 (95%CI: 0.59-0.67) and 0.65 (95%CI: 0.61-0.69), respectively (p=0.389). In Cohort B, three risk factors were identified as independent predictors of short survival. Patients were also divided into the oligo group and the non-oligo group. The C-index between Model B and IMDC risk model was 0.62 (95%CI: 0.59-0.64) and 0.61 (95%CI: 0.58-0.64), respectively (p=0.650). For Model A, mOS for non-oligo group was 13.4 months vs NR in oligo group (3y OS: 25.3 vs 51.8%), while for model B, mOS was 18.5 vs NR respectively (3y OS: 24.3 vs 57.5%). With the novel prognostic models, patients in the IMDC intermediate risk group could be further stratified into oligo group (mOS: NR; 3y OS: 55.6%) that had a better outcome than patients in non-oligo group (mOS: 19.2 month; 3y OS: 24.9%; p<0.001). Conclusions: Compared with the current IMDC model, the novel prognostic models of oligometastatic mRCC could well distinguish patients into favorable and poor prognostic groups with fewer risk factors and comparable predictive power. Meanwhile, the novel models can better stratify the IMDC intermediate risk group into oligo and non-oligo groups with significantly different OS outcomes, and is more conductive to the comprehensive treatment of patients with mRCC.