Cancer related antigens with special reference to casein in breast cancer

It has been known for more than 15 years that various tumours can secrete polypeptide hormones such as acth, parathormone, calcitonin...However, the presence of these hormones has no specificity as far as the presence of the tumor is concerned. On the other hand, it has been shown that tumor cells regain the property of synthesizing casein, this product of the exocrine secretion of the breast is only present during lactation under physiological circumstances. It can, however, be found in the serum of patients with breast cancer and also in a significant percentage of the sera of subjects with gastrointestinal and pulmonary neoplasms. This fact indicates the existence of ectopic exocrine secretion which has a greater specificity for the presence of a neoplasm. (G.C.)