Abstract
Immunohistochemical staining of E-cadherin and thymidine phosphorylase (TP) were performed on paraffin-embedded blocks from needle biopsy specimens of prostate cancer. Specimens were obtained from 20 patients (mean age : 72.9 years, range : 65-94 years) who underwent prostate needle biopsy under transrectal ultrasound guide in 1998. Prostate cancer was suspected in patients when a high serum prostate-specific antigen (PSA) level was observed and suspicious findings from a digital transrectal examination (DRE) or transrectal prostate ultrasonograph (TRUS) were obtained. The immunohistochemical staining results were compared with the Gleason score and clinical stage of the disease. Although a high level of expression of E-cadherin was observed in all patients with prostatic hypertrophy or prostatitis, a reduction in E-cadherin expression was seen with an increase in Gleason score and clinical stage of the disease, indicating a correlation of E-cadherin expression with both parameters. Non-cancerous epithelial cells had very high TP expression levels, while cancer tissue demonstrated a metachromatic pattern. There was considerable heterogeneity in the topographic distribution of TP expression, indicating that there was no significant correlation with either the Gleason score or clinical stage. There was no evidence of a common expression pattern between E-cadherin and TP. TP was highly expressed in stroma, irrespective of the differentiated state of the cancer, this resulted in inconsistent staining, while E-cadherin showed expression levels that correlated with the Gleason score. These findings indicate that TP expression level is not suitable to use as a single indicator of malignancy in prostate cancer. E-cadherin may be considered to be a marker of malignant phenotype in prostate cancer due to the presence of a significant correlation of expression levels with the Gleason score and clinical stage of disease. Moreover, immunostaining proved to be feasible using stored paraffin-embedded blocks. However based on the results of the present study, it could not be said that E-cadherin has a greater diagnostic value in the prediction of prognosis than the Gleason score.
