Most microprolactinomas and macroprolactinomas respond well to medical therapy with ergot-derived dopamine agonists, including bromocriptine and cabergoline. For many patients, cabergoline has a more satisfactory side-effect profile than bromocriptine. Cabergoline therapy may be successful in treating patients whose prolactinomas are resistant to bromocriptine or who cannot tolerate bromocriptine; this therapy has a success rate of more than 90% in patients with newly diagnosed prolactinomas.[8,9,10] In a prospective study, cabergoline was safely withdrawn in patients with normalized prolactin levels and no evidence of tumor, which may effect a cure rate of approximately 70%. On the basis of its safety record in pregnancy, however, bromocriptine is the treatment of choice when restoration of fertility is the patient's goal. Microprolactinomas change little in size with treatment, but macroprolactinomas can be expected to shrink, sometimes quite dramatically. Microprolactinomas may decrease in size over time and have been observed to undergo complete, spontaneous resolution on occasion. Surgery is typically reserved for those patients who cannot tolerate dopamine agonists, who suffer pituitary apoplexy during treatment, or whose macroprolactinomas are not responsive to medical therapy.
Treatment for acromegaly includes surgical, radiation, and medical therapies. Microadenomectomy or macroadenoma decompression is approached transsphenoidally in most patients. Increasingly, endoscopic surgery is used to allow the entire surgical field to be viewed and to allow tumor tissue that would otherwise be inaccessible with rigid instruments to be safely resected. Complete return of GH concentrations to normal, however, is not often achieved. Adjunctive radiation therapy is increasingly reserved for tumors that extend beyond the safe operative area and appear to pose an ongoing threat. Drug treatment includes the use of somatostatin analogues, dopamine analogues, and the GH-receptor antagonist, pegvisomant. As the first of a new class of GH receptors, pegvisomant works by inhibiting functional dimerization of GH receptors, and thereby inhibits GH action. Preliminary results indicate that it may be the most effective medical treatment for acromegaly reported to date.[14,15] In acromegalic patients, impaired glucose tolerance, hypertension, and hyperlipidemia should be vigorously treated concurrently with definitive therapy. A multidisciplinary clinical approach may be required for the treatment of arthritis, carpal tunnel syndrome, obstructive sleep apnea, and prognathism. Mortality is related primarily to cardiovascular and respiratory diseases.
For corticotroph adenomas, transsphenoidal microsurgery is the treatment of choice.[3,6] Remission rates reported in most series are approximately 70% to 90%. In a series of 216 patients who had surgery using a transsphenoidal approach, 75% experienced long-term remission, 21% experienced persistence of Cushing disease, and 9% had recurrence after the initial correction of the hypercortisolism. The average time interval for reoperation was 3.8 years. Seventy-nine percent of the tumors were microadenomas, and 18% were macroadenomas; 86% of the cases with microadenoma had long-term remission, whereas, only 46% of those with macroadenoma had remission. In cases in which hypercortisolemia persists, early repeat exploration and/or radiation therapy or laparoscopic bilateral adrenalectomy may be required. Drug therapy is considered an adjunct to transsphenoidal microsurgery in cases in which there is residual tumor, and in cases in which one is awaiting the effects of the radiation therapy. Ketoconazole, an inhibitor of steroidogenesis, is considered the first drug of choice. Radiation therapy has been used in patients who are deemed to be poor surgical candidates and has also been used as adjunctive therapy in patients with residual or recurrent active tumor. If untreated, patients frequently succumb to cardiovascular disease or infection.