Immunohistochemical staining of ras p21: staining in benign and malignant prostate tissue

A total of 124 specimens of prostate tissue (25 normal prostate, 41 benign prostatic hyperplasia, 58 adenocarcinoma) was immunostained for ras p21 using a commercially available monoclonal antibody directed against a peptide sequence conserved among all members of the ras gene family. Of normal prostate specimens, 76% showed no staining while the remainder showed only weak epithelial (glandular) staining. No significant stromal staining was noted in any normal prostate specimen. In contrast most benign prostatic hyperplasia specimens showed abundant staining. Epithelial staining was observed in 88% and stromal staining in 73% of specimens. A majority of prostate carcinoma specimens also stained, with 62% and 36% showing epithelial and stromal staining, respectively. No association was noted between staining and either tumor grade or clinical stage. These data argue against any clinical usefulness of immunostaining for ras p21 in the diagnosis or grading of prostate cancer.