[Biological markers of cancer. Critical study]

The clinical use of tumor-associated markers still raises several problems, due to the lack of specificity of most biological markers and to insufficient evaluation of their true benefit for the patients. Only two markers, calcitonin and alpha-fetoprotein, markers of medullary thyroid carcinomas and of hepatocellular carcinomas respectively, have been proved useful in screening high risk populations for tumors. The usefulness of the prostate specific antigen in screening for prostatic cancer is still debated. Human chorionic gonadotropin and its free beta subunit are useful in the early detection of testicular cancer. Other biological makers, such as CA 15-3 for breast cancers, CA 19-9 for either gastric or pancreatic cancers, anc CA 125 for ovarian tumors are useful mostly in the follow-up of these tumors. Finally, measurements of tumor markers and analysis of their results must be performed by biologists or physicians who use tumor-associated markers routinely.