High peritumoral Bmi-1 expression is an independent prognosticator of poor prognosis in renal cell carcinoma.

B lymphoma Mo-MLV insertion region 1 homolog (Bmi-1) is a transcriptional repressor, which plays important roles in the development of cancers, but the function of Bmi-1 in kidney tumorigenesis and its prognostic values remain unclear. This study aims to investigate prognostic values of the intratumoral and peritumoral expression of Bmi-1 in patients with renal cell carcinoma. Expression of Bmi-1 was assessed by immunohistochemistry in specimens containing paired tumor and peritumoral renal tissue from 241 patients who had undergone curative nephrectomy at Zhongshan Hospital from 2005 to 2007. The association of Bmi-1 expression with clinical and pathological parameters and outcomes was investigated. Specific expression of Bmi-1 was found both in peritumoral and intratumoral tissues. High expression of Bmi-1 in peritumoral but not intratumoral is significantly associated with poor overall survival (OS) (P < 0.001) and relapse-free survival (RFS) (P = 0.003). Furthermore, Bmi-1 expression was identified as an independent prognostic factor for OS, and combination of peritumoral Bmi-1 and tumor node metastasis (TNM) stage had a better power to predict the patients' death and disease recurrence. High peritumoral Bmi-1 expression can serve as an independent prognostic biomarker and could be a novel therapeutic target for renal cell carcinoma (RCC).