Heterogeneity of cathepsin B and stefin A expression in gleason pattern 3+3 (score 6) prostate cancer needle biopsies

Background: There is a significant positive association of increased ratios of cathepsin B to its endogenous inhibitor stefin (cystatin) A in prostatectomy tumors with pelvic lymph node metastases. Needle biopsy diagnosis of prostate cancer is critical in initial treatment selection. The objective was to characterize cathepsin B and stefin A immunostaining patterns in needle biopsies of histologically similar Gleason pattern 3+3 (score 6) foci in relation to pretreatment clinical data. Materials and Methods: Immunostaining of cathepsin B and stefin A of 65 biopsy sections were imaged, quantified and analyzed with Student's t-test (p<0.05). Results: Patients had T1c to T3b clinical stages and pre-surgery total prostate-specific antigen serum levels from 1.25 to 20.0 ng/ml. Cathepsin B and stefin A reaction products were found in the cytoplasm of basal and columnar/cuboidal cells of benign prostatic hyperplasia (BPH), prostatic intraepithelial neoplasia (PIN) and neoplastic cells. Ratios of cathepsin B to stefin A were significantly higher in prostate cancer when compared to that in BPH and PIN glands. Conclusion: Small foci of Gleason pattern 3+3 tumors in needle biopsies have heterogeneous cathepsin B and stefin A immunostaining. Stratification of these tumors in relation to clinical stage by cathepsin B and stefin A may assist in treatment selection.