Current Indications for the Surgical Treatment of Prolactinomas

Introduction: Prolactin-secreting lesions represent the most common subtype of all pituitary tumors, approximately 40% of diagnosed pituitary adenomas. Prolactinomas are unique in that they are the only type of pituitary adenoma that can be treated quite effectively with medications in the form of dopamine agonists (DAs). Transsphenoidal surgery (TSS) may be indicated in prolactinoma patients who are resistant to DA therapy, intolerant of their side effects, or both. Approximately 10% of patients will fail medical therapy and have no tumor shrinkage, refractory serum prolactin levels, and/or intolerable side effects of DAs, and subsequently become candidates for surgical resection. We examine the current indications for TSS in the prolactinoma patient population. Methods: Medical records from a single, large volume, academic center were retrospectively reviewed. Overall, 66 consecutive prolactinoma patients who underwent transspenoidal resection (with subsequent pathologic confirmation) over a 6-year period (April 2008 to April 2014) were included in this study. The outcomes of interest were normalization of prolactin (with or without DA), reduction in mass effect on optic apparatus, and resolution of symptoms of intolerance. Complications were also analyzed, including symptomatic inappropriate antidiuretic hormone secretion (SIADH), diabetes insipidus (DI), CSF leak, and visual changes among others. Results: Overall, 66 patients were included in the study (44 women, mean = 36 years, SD = 10.4 years; 22 men, mean = 41.7 years, SD = 12.8 years). Most patients had received cabergoline alone (n = 30, 66.7%), or cabergoline in conjunction with bromocriptine (n = 12, 26.7%) before surgery. The median follow-up time was 12.0 months (range, 3–69 months). The total number of DA intolerant patients was 29 (43.9%). Postoperatively, 18 intolerant patients (66.7%) had normalized prolactin levels without any DA therapy, and 5 patients (17.2%) required a DA to normalize their prolactin levels (p = 0.02). Six patients (20.6%) had persistently elevated prolactin levels but were no longer receiving DA treatment (p < 0.001). The total number of patients presenting with dopamine resistance was 29 (43.9%). Postoperatively, 10 patients (35.7%) had a normal prolactin level without DA therapy, and 7 patients (25%) were treated with DA therapy to normalize the prolactin level (p = 0.22). Eight patients (28.6%) still had supraphysiologic prolactin levels, but they were no longer taking a DA (p < 0.001). Three patients (10.7%) were hyperprolactinemic despite treatment with a DA postoperatively (p ≤ 0.001). The percentage of patients who developed either transient SIADH or DI was 12.1% (n = 8). Conclusion: Transsphenoidal surgery is indicated in prolactinoma patients who are resistant to DA therapy, intolerant of their side effects, or both. Recent advance in endoscopic technology and increasing surgeon comfort with this technology are making transsphenoidal procedures safer, faster, and more effective. After an appropriate treatment interval with multiple DAs, radiographic follow-up, and careful clinical evaluation, prolactinoma patients can be offered surgery as an effective therapeutic option. It should be emphasized that the majority of resistant and intolerant prolactinoma patients will regain normal prolactin levels and tumor shrinkage after transsphenoidal surgery, with minimal complications.