Long-term outcome of patients with macroprolactinomas initially treated with dopamine agonists.

OBJECTIVE: Dopamine agonists are the first line therapy for the treatment of prolactinomas. The aim of this study was to assess the outcome of macroprolactinomas during long-term follow-up after initial treatment with dopamine agonists.

DESIGN: Retrospective follow-up study.

PATIENTS: We included 72 consecutive patients (age 39+/-17 years, men 46%) diagnosed with macroprolactinoma, and initially treated with dopamine agonists between 1980 and 2004.

RESULTS: Initial presentation included headache in 49%, and visual field defects in 38% of the patients. Nine patients were already treated with dopamine agonists at presentation. Median prolactin level of the untreated patients was 460 microg/L (range 96-35,398 microg/L) at presentation. Hypopituitarism, other than hypogonadism, was present in 6% of the patients. Mean duration of follow-up was 10.2+/-6.1 years. Additional transsphenoidal surgery was necessary in 35% of the patients, because of resistance and/or intolerance of dopamine agonists. Postoperative radiotherapy was provided to 18% of all patients. During long-term follow-up, normoprolactinemia was present in 85% of the patients, but biochemical remission (normal prolactin levels in the absence of dopamine agonists) was present in only 22% of the patients. Tumor shrinkage was evident on MRI in 57% of the patients. Hypopituitarism developed in 39% of the patients, especially in those who received additional surgery with or without radiotherapy.

CONCLUSION: Dopamine agonists are effective in normalizing prolactin values, and inducing tumor shrinkage. However, in one-third of the patients, additional therapy was necessary due to dopamine agonist resistance and/or intolerance, associated with a high incidence of hypopituitarism.