BioScore (B7-H1, survivin, and Ki-67) does not predict cancer-specific mortality in surgically treated patients with renal cell carcinoma: An external validation study.

ABSTRACT

BACKGROUND: To externally validate' BioScore', a biomarker-based scoring system using immunohistochemical tumor expression levels of B7-H1, survivin, and Ki-67, in a single-center cohort of renal cell carcinoma (RCC) patients. Additionally, we investigated the potential benefit of BioScore as compared to the Mayo Clinic stage, size, grade, and necrosis (SSIGN) score. MATERIALS AND METHODS: The validation cohort comprised 393 nonmetastatic RCC patients treated with radical nephrectomy or nephron-sparing surgery from 1999 to 2004. Kaplan-Meier estimators, the log-rank test, uni- and multivariable Cox regression models, and measures of discrimination were used to quantify the prognostic performance of BioScore regarding cancer-specific mortality (CSM). RESULTS: During a median follow-up of 7.8 years, 69/132 (52%) deaths were adjudicated to progressive disease. BioScore was weakly associated with CSM in univariable analysis (hazard ratio per 1 point increase = 1.12, 95% confidence interval = 1.02-1.23, P = 0.023). However, this association did not prevail after adjusting for other adverse prognostic factors as represented by the SSIGN score. The discriminative performance of BioScore was very modest (Harrell's C-Index = 0.60) and did not improve the SSIGN score (P = 0.341), which already showed an excellent discrimination, as evidenced by Harrell's C-Index of 0.81. In a sensitivity analysis regarding clear cell RCC patients only, B7-H1 positivity did not emerge as a statistically significant predictor of CSM. CONCLUSION: Although a higher BioScore was significantly associated with a higher CSM, the magnitude of this association was weak and not independent from other prognosticators. Moreover, BioScore did not improve the prognostic accuracy of the SSIGN score.