Prolactin-secreting adenomas: the preoperative response to bromocriptine treatment and surgical outcome

Controversy exists regarding the effects of bromocriptine on the success of transsphenoidal surgery for patients with prolactinomas. Various studies on this drug have reported adverse effects, improvement, and no effect upon the subsequent surgical outcome. The authors have retrospectively reviewed the case histories of 55 patients with immunocytochemically confirmed prolactin-secreting pituitary adenomas operated on by a transsphenoidal approach between 1981 and 1985. All patients had received bromocriptine in a variety of doses and for variable durations prior to surgery. Thirty-nine patients were women and 16 were men, with an age range of 8 to 72 years. Basal prolactin levels prior to bromocriptine treatment ranged from 38 to 100 ng/ml in 11 patients, from 101 to 200 ng/ml in 12, and greater than 200 ng/ml in 29. The "cure" rates were 54%, 58%, and 38%, respectively. Thirty-one patients had microadenomas, with a postoperative cure rate of 68%; 12 had diffuse expansive adenomas, with a 17% cure rate; and 12 had grossly invasive tumors, with a 17% cure rate. A response to preoperative bromocriptine therapy was defined as a return of the basal prolactin level to normal: 18 patients were responders and 29 were hyporesponders; in eight the data were not available. The postoperative cure rate was 50% for the responders and 31% for the hyporesponders. Taking into account the distribution of tumor type, there was no actual difference in outcome between the responder and the hyporesponder groups. The total bromocriptine dose received preoperatively was nearly identical for all groups. No significant differences in the frequency or extent of fibrosis, calcification, or prolactin immunoreactivity were observed in the 55 patients when compared with 26 control prolactinomas not treated with bromocriptine. It is concluded that short-term bromocriptine treatment does not adversely affect surgical outcome in any of the prolactin-secreting adenoma groups, nor does response or lack of response to bromocriptine predict surgical outcome.