Casein and other tumor markers in relation to cancer of the breast.
Five tumor markers can be simultaneously determined in the serum by radioimmunoassay: carcinoembryonal antigen (CEA), alpha-fetoprotein (alpha-FP), human chorionic gonadotropin (HCG), beta-subunit of HCG (beta-HCG) and kappa-casein. In a series of 935 healthy subjects, these antigens remain detectable or are detected within very precise limits. At the start of the clinical evolution of breast cancer, the incidence of pathological concentrations is increased as compared with the highest level observed in normal subjects. This high incidence is mainly due to a concomitant determination of CEA, kappa-casein, HCG and beta-HCG. The alpha-FP test is never positive, while the kappa-casein concentration is particularly high in the first clinical stages of breast cancer and with metastases. The concomitant determination of these tumor markers may be a biological element contributing to the diagnosis of neoplasia, although it is neither an absolute nor a specific criterium. Indeed, a pathological concentration of at least one antigen was observed in 5.5% of the subjects presenting with benign mastopathy. When metastases occur (25 patients), the incidence of pathological concentrations of at least one antigen increases: 88%, the absolute values of these levels increasing simultaneously. The determination of the antigen concentration therefore allows an evaluation of the extension of the disease. Surgical removal reduces the incidence of positivity of these antigens to 34%. Persistence of pathological levels seems to be related to a possibility of relapse or metastatic spreading. Finally, chemotherapy and radiotherapy applied on a tumor which is not excised, does not decrease the incidence of positivity of the tumoral markers, although their levels seem to fluctuate with the clinical evolution.