Ectopic Production of Hormones and Other Proteins by Tumors

It is becoming possible to classify certain tumors together on the basis of proteins, especially hormones, that they produce, and such a classification lends support to the hypothesis that the neoplastic process involves dedifferentiation, in which cells return to an earlier, sometimes embryonic stage of development. Some portions of the schema are even now clinically useful in the diagnosis and management of malignancies.