Introduction and objective: With a limited number of prognostic and predictive biomarkers available, carbonic anhydrase-IX (CAIX) has served as an important prognostic biomarker for patients with clear cell renal cell carcinoma (ccRCC). However, studies have recently called into question the role of CAIX as a biomarker for ccRCC. To investigate this uncertainty, we quantified the association of CAIX with lymphatic involvement and survival using data from ARISER study (WX-2007-03-HR)--a prospective trial involving subjects with high-risk nonmetastatic ccRCC.
Methods and materials: We reviewed the records of 813 patients enrolled in the ARISER study. Central review of histology, grade, and CAIX staining (frequency and intensity) was performed. CAIX score was derived by multiplying the staining intensity (1-3) by percent positive cells (0%-100%), yielding a range of 0 to 300. We quantified the association of CAIX expression and score with lymphatic spread and survival (disease-free survival [DFS] and overall survival [OS]) using Kaplan-Meier and multivariable propensity score adjusted Cox regression analyses.
Results: Median follow-up of the cohort was 54.2 months. Although 56% of subjects with lymphatic involvement had CAIX>85%, only 33% had CAIX score ≥ 200. On multivariable analysis, CAIX>85% was not a statistically significant predictor of DFS and OS (P = 0.06 and P = 0.15, respectively). However, CAIX score ≥ 200, when compared with CAIX score ≤ 100, was associated with improved DFS and OS (P = 0.01 and P = 0.01, respectively) on multivariable analysis.
Conclusions: The largest, multicenter, prospective analysis of patients with high-risk nonmetastatic ccRCC demonstrates the utility of CAIX score as a statistically significant prognostic biomarker for survival. We recommend that CAIX score be quantified for all patients with high-risk disease after nephrectomy.
Keywords: Adjuvant therapy; CAIX; Clinical trial; Prognostic biomarker; Renal cell carcinoma.
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