Prostate tumors antibodies

Tables 8 and 9 show how some of the previously mentioned antibodies can distinguish between metastatic adenocarcinomas of unknown primaries in females and males, respectively. The panels are similar except for ERP (estrogen receptor protein), GCDFP-15, and S-100, which are used in females for their specificity for gynecologic tumors and PSA (prostatic specific antigen), used in males for its specificity for prostatic adenocarcinoma. These antibodies cannot absolutely distinguish among the tumor sources listed. However, they can guide pathologists and clinicians on which organs need to be further examined to determine the primary source of a metastatic tumor.

Prewett M, Rockwell P, Rockwell RF, et al. The biologic effects of C225, a chimeric monoclonal antibody to the EGFR, on human prostate carcinoma. J Immunother Emphasis Tumor Immunol 1996 19 419-427. 

Liu, B., F. Conrad, M. R. Cooperberg, D. B. Kirpotin and J. D. Marks (2004). Mapping tumor epitope space by direct selection of single-chain Fv antibody libraries on prostate cancer cells. Cancer Res 64(2) 704-710. 

With few exceptions, an increase in the activity or mass of an enzyme or isoenzyme is not specific or sensitive enough to be used for identifying the type of cancer or the specific organ involvement. An exception is PSA. PSA has mild protease activity and amino acid sequence homology with serine protease of the kallikrein family.It is expressed by normal, benign, hyperplastic, and cancerous prostate glands and minimally by other tissue. Until the application of PSA as a marker for prostate cancer, tumor enzymes had lost most of their popularity for use as cancer markers. Enzymes were used historically as tumor markers before the discovery of oncofetal antigens and the advent of monoclonal antibodies. The abnormalities of enzymes as a marker for cancer are either the expression of the fetal form of the enzyme (isozyme) or the ectopic production of enzymes. 

Neoplasms that are essentially negative with most CEA antibodies include adenocarcinomas of prostate, kidney, adrenal gland, and endometrium,220 along with serous ovarian tumors and mesotheliomas. Liver cell-derived tumors are nonreacti ve with the monoclonal CEA antibodies but do react with the polyclonal antibodies... 

Together, antibodies to PSA and prostatic acid phosphatase (PAP) will stain more than 95% of prostate carcinomas, but there are some caveats. The immunostaining of tumor cells falls off with increasing Gleason grade with both antibodies, and PAP is found in a wide variety of other tumors including hindgut carcinoid tumors.PSA has been found... 

PSA has been found to stain scattered tumor cells from cutaneous malignant melanoma and its metas-tases." This should not create a diagnostic dilemma because prostate cancers are strongly and diffusely positive with LMW keratin antibodies such as CAM5.2, which is another illustration of the necessity of examining tumors with a panel of antibodies. 

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