Effectiveness of long-term cabergoline treatment for giant prolactinoma: study of 12 men.

OBJECTIVE To review our experience with cabergoline, a D2-selective dopamine agonist, for the treatment of giant prolactinomas. DESIGN A retrospective case series; descriptive statistics. METHODS The study group included 12 men aged 24-52 years (mean 39.2 years) treated for giant prolactinoma at our centers from 1997 to 2006. Cabergoline was started at a dose of 0.5 mg/three times a week and progressively increased as necessary to up to 7 mg/week. Patients were followed by hormone measurements, sellar magnetic resonance imaging, and visual examinations. RESULTS In ten patients, cabergoline served as first-line therapy. The other two patients had previously undergone transsphenoidal partial tumor resection because of visual deterioration. Mean serum prolactin level before treatment was 14,393 +/- 14,579 ng/ml (range 2047-55,033 ng/ml; normal 5-17 ng/ml). Following treatment, levels normalized in ten men within 1-84 months (mean, 25.3 months) and decreased in the other two to 2-3 times of normal. Tumor diameter, which measured 40-70 mm at diagnosis, showed a mean maximal decrease of 47 +/- 21%; response was first noted about 6 months after the onset of treatment. Nine patients had visual field defects at diagnosis; vision returned to normal in three of them and improved in five. Testosterone levels, initially low in all patients, normalized in eight. There were no side effects of treatment. CONCLUSION Cabergoline therapy appears to be effective and safe in men with giant prolactinomas. These findings suggest that cabergoline should be the first-line therapy for aggressive prolactinomas, even in patients with visual field defects.