Cabergoline: a first-choice treatment in patients with previously untreated prolactin-secreting pituitary adenoma

Cabergoline (CAB) treatment is an effective, safe and well tolerated approach for hyperprolactinemia. We investigated the efficacy of 24-month treatment with CAB in 37 patients with previously untreated PRL-secreting pituitary adenoma and evaluated the hormonal and neuroradiological changes after the discontinuation of long-term therapy. Eleven patients with macroprolactinoma (1M/10F) and 26 with microprolactinoma (4M/22F) started treatment taking 0.25 mg CAB twice a week for 4 weeks. The dose was increased stepwise in 0.5 mg increments until reaching lowest maximally effective and tolerated dose. CAB was withdrawn before the end of the study in 6 women who became pregnant and in one patient who showed a slight increase of the macroadenoma at MRI. During treatment, PRL levels decreased significantly in macro (11.1+/-1.1 vs 407.8+/-98.3 microg/l, p<0.001) and microprolactinomas (11.1+/-1.6 vs 193.8+/-23.4 microg/l, p<0.05) and normalized in all macro and in 23/26 microprolactinomas. In 3 cases PRL levels decreased but did not normalize because the appearance of side effects, such as nausea or hypotension, prevented the increase of the dose of CAB. The effective dose of drug correlated significantly with basal serum PRL levels (p<0.05) and with the pituitary tumor size (p<0.05). A significant decrease of the mean adenoma size was evident for macro (6.9+/-1.8 vs 16.0+/-1.8 mm, p<0.001) and microprolactinomas (3.0+/-0.5 vs 6.5+/-0.4 mm, p<0.001) at MRI. The tumor disappeared in 4 macroadenomas and in 11 microadenomas after 12 months of treatment. CAB withdrawal was followed by serum PRL increase in 13 cases after 3 months, in 6 after 6 months, in 2 after 9 months, and in one patient at the 12th month. Five patients showed normoprolactinemia with negative MRI after one year. Regular menses were restored in 7/10 macroprolactinomas and in all oligo-amenorrhoic patients with microadenoma; serum testosterone levels normalized in 2/3 hypogonadic men. Five out of 6 women become pregnant and had uneventful pregnancies which resulted in deliveries of normal babies. In conclusion, this study confirms the effectiveness and safety of CAB for patients with PRL-secreting pituitary adenoma and suggests that it can be considered a first choice treatment.