Pre-treatment and post-treatment evaluation of prostatic adenocarcinoma for prostatic specific acid phosphatase and prostatic specific antigen by immunohistochemistry.

Prostatic specific acid phosphatase and prostatic specific antigen have been used as specific markers of prostatic adenocarcinoma in immunohistochemical studies, particularly when seeking the primary site of a poorly differentiated metastasis. We herein evaluate the effect of therapy on the persistence of these markers in surgically obtained tissues. Prostatic biopsies from 30 patients with adenocarcinoma of the prostate gland before and after treatment with orchiectomy alone, diethylstilbestrol, external beam radiation or combined radiation and diethylstilbestrol were studied for prostatic specific acid phosphatase and prostatic specific antigen using the indirect immunoperoxidase technique. The interval between biopsies ranged from 3 to 72 months, with an average of 28 months. All pre-treatment biopsies stained positively for prostatic specific acid phosphatase and prostatic specific antigen. Staining for prostatic specific antigen and prostatic specific acid phosphatase was seen easily in 29 of 30 post-treatment biopsies, while in 1 case infiltrating anaplastic cells surrounded by stroma showed staining for these antigens in an extremely small percentage of cells, which were overlooked easily unless examined carefully. In view of this small number of positively staining cells this case was designated as equivocal. While some cases demonstrated less intense staining in post-treatment biopsies compared to pre-treatment, this finding was by no means constant. With these primary antisera a higher percentage of cytologically malignant cells stained positively for prostatic specific acid phosphatase than for prostatic specific antigen in adjacent tissue sections in some cases. Prostatic specific acid phosphatase and prostatic specific antigen appear to be sensitive and persistent markers of prostatic adenocarcinoma despite morphologic changes accompanying various therapies.