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.