Ectopic (inappropriate) hormone production by tumors: Mechanisms involved and the biological and clinical implications

THE PRODUCTION of hormones and other “marker proteins” by tumors has come to play an increasingly important role for clinicians involved in the diagnosis and management of patients with neoplasia and for investigators involved in basic studies of tumor biology and endocrinology. It has become apparent during the past 30 to 40 years that a wide range of endocrine tumors secrete hormones not normally associated with the gland in which the neoplasm arises and that nonendocrine tumors can synthesize and/or secrete certain polypeptide hormones and other “tumor-associated” proteins. The production of such tumor markers has come to be referred to as “ectopic” or “inappropriate” when the marker in question is not obviously associated with the tissue from which the tumor derives. Since the recognition of this aspect of tumor behavior, considerable attention has been focused on the ectopic endocrine syndromes which may arise in patients with cancer because of such protein production, and on the important clinical implications of these syndromes for diagnosis and patient management.