Dopamine agonists are approximately 80% to 90% effective in decreasing prolactin levels and reducing tumor size in microadenomas and 60% to 70% in macroadenomas. The major drawback of using medication is that it does not always provide permanent results. Hyperprolactinemia and tumor growth can resume upon discontinuation of the drug, even if the patient has taken it for several years.1 The rate of recurrence after discontinuing therapy can be anywhere from 26% to 69%, and the highest likelihood occurs within a year of withdrawal.4 Close clinical follow-up is thus important.
Surgery, typically a transphenoidal resection, is performed by a neurosurgeon. Success of surgery is based on tumor size and basal prolactin level prior to the procedure. It is more effective in restoring normal prolactin levels and resolution of symptoms in microadenomas than in macroadenomas. Progressive vision loss, pituitary apoplexy, and intolerance to dopamine agonists are indications for surgery.1
Radiation therapy is reserved for those patients who have residual tumors postsurgery and have not responded to or are intolerant to dopamine agonists. Response to radiation is slow; it can sometimes take several years to achieve full effect. Gamma-knife radiation is sometimes used, but experience with this procedure is limited thus far in prolactinomas.
Overall, the vast majority of prolactinomas are benign and fairly straightforward to manage clinically.3
REFERENCES
1. Greenspan F, Gardner D. Basic & Clinical Endocrinology, 7th ed. New York: McGraw-Hill; 2004.
2. Ciccarelli A, Daly A, Beckers A. The epidemiology of prolactinomas. Pituitary. 2005;8(1):3-6.
3. Casanueva FF, Molitch ME, Schlechte JA, et al. Guidelines of the Pituitary Society for the diagnosis and management of prolactinomas. Clin Endocrinol (Oxf). 2006;65(2):265-273.
4. Melmed S, Casanueva FF, Hoffman AR, et al. Diagnosis and treatment of hyperprolactinemia: an Endocrine Society Clinical Practice Guideline. J Clinical Endocrinol Metab. 2011;96(2):273-288.