Medical therapy of glycoprotein hormone-secreting pituitary tumors.

Glycoprotein hormone adenomas represent approximately 25% of all pituitary adenomas. Although surgery and radiation are the primary therapeutic modalities, there is an important need for the development of adjunctive medical therapy for these tumors. Investigations have focused on the suppression of GPH synthesis and secretion by hypothalamic regulatory factors in an attempt to decrease tumor mass. Although GnRH agonist analogues have not produced consistent GPH suppression, they may be valuable tools to investigate the regulation of intact GPH and subunit secretion in these tumors. Preliminary reports have shown that analogues of dopamine and somatostatin may be therapeutically useful. However, careful in vivo and in vitro characterization of tumors within this very heterogeneous group and correlation with their response to treatment are needed to establish guidelines for effective medical therapy.