Evaluation of commercial immunoperoxidase kits for prostatic specific antigen and prostatic specific acid phosphatase

The practical application of commercially available immunoperoxidase kits for prostatic specific antigen (PSA) and prostatic specific acid phosphatase (PSPH) were blindly evaluated on routinely formalin fixed and paraffin embedded tissue from 95 consecutive cases of prostatic carcinoma, 10 cases of metastases from prostatic carcinoma and 90 cases of primary or metastatic non prostatic carcinoma. Both Kits showed a diagnostic specificity of 100%. The diagnostic sensitivities were 94% (PSA) and 90% (PSPH) respectively, but concomitantly staining for PSA and PSPH improved the diagnostic sensitivity to 99%. Using the histologic grading system of Gleason both markers showed a tendency to less extensive staining in low differentiated prostatic carcinomas. It is concluded that both Kits are highly specific and highly sensitive, but negative reaction in medium or low differentiated adenocarcinomas does not rule out the possibility of prostatic carcinoma.