Expression of MIB-1 in prostatic carcinoma: An immunohistochemical study

ABSTRACT

Immunohistochemical assessment of MIB-1 expression in prostatic carcinoma as a proliferation marker and the correlation between the immunohistochemical findings and the most important prognostic factors of prostatic carcinoma. The specimens of 60 cases of prostatic carcinoma were retrospectively reviewed. The study material included 20 [33%] radical prostatectomy specimens, 10 [17%] specimens from transurethral resection of the prostate [TURF] and 30 [50%] specimens of transrectal ultnasonography [TRUS]-guided biopsies. The archival formalin-fixed paraffin- embedded blocks were collected and immunohistochemically stained for Ki-67 [MIB-1]. The results of the immunohistochemical staining were correlated with Gleason score, tumor stage, Mostofi-WHO nuclear grade, perineural infiltration and pre-operative PSA level. There was a statistically significant correlation between MIB- I immunoneactivity and increasing Gleason score and Mostofi-WHO nuclear grade. MIB-1 positivity was significantly higher in patients with tumor stage C and in cases with a pre-operative PSA >10 ng/ml. Cases with evidence of perineural invasion showed a higher percentage of moderate and marked MIB- 1 immunoreactivity than cases without perineural invasion, but this difference was not statistically significant. The proliferative index measured by the expression of the Ki-67 protein [using the Ki-67 antibody clone MIB-1] correlated significantly with most of the well established prognostic factors in prostatic carcinoma. MIB-1 expression could serve as a prognostic factor in prostatic carcinoma using standardized immunohistochemical methods: