PROSTATE-SPECIFIC ANTIGEN A Clue for the Prostatic Origin of Metastasis
The prostate-specific antigen is a recently purified glycoprotein which is present only in the prostatic gland. In order to confirm the usefulness of this protein in isolating prostatic carcinomas from socalled metastatic carcinomas of unknown primary site, we immunohistochemically studied 19 non-neoplastic prostatic tissue, 18 primary carcinomas of the prostate, and 32 non-prostatic adenocarcinomas. From our study, we concluded that PSA is highly specific for the prostatic carcinomas. The absence of PSA, however, does not necessarily rule out its prostatic origin when the tumor is poorly differentiated. In our laboratory, from now on, PSA will be applied routinely in cases of metastatic carcinomas of unknown origin.