PROLACTINOMAS RESISTANT TO STANDARD DOPAMINE AGONISTS RESPOND TO CHRONIC CABERGOLINE TREATMENT

Cabergoline (CAB), a new, potent, and long-lasting PRL-lowering agent, was shown to be effective in tumoral hyperprolactinemia. The aim of t his study was to investigate the effectiveness of CAB in patients with prolactinoma proven to be resistant to bromocriptine (BRC) and quinag olide (CV 205-502). Twenty-seven patients (19 macro- and 8 microprolac tinomas) were treated with CAB at a weekly dose of 0.5-3 mg for 3-22 m onths. All patients were previously shown to be resistant to BRC, and 20 of them were resistant to CV 205-502 as well. Basal serum PRL level s before CAB treatment ranged from 108-3500 mu g/L in macroprolactinom as and from 64-205 mu g/L in microprolactinomas. Gonadal failure was p resent in all patients, whereas symptoms of tumor expansion, such as v isual field defects and headache, were present in 10 of 27 patients. E ight macroprolactinomas had previously undergone surgery and/or radiot herapy. CAB treatment normalized seruin PRL levels in 15 of 19 macropr olactinomas and in all 8 microprolactinomas. In 3 of the remaining 4 p atients it caused a notable decrease in prolactinemia (89%, 80.5%, and 68.7% of the baseline). Only 1 patient was withdrawn from CAB therapy after 3 months at the weekly dose of 2 mg due to the absence of any s ignificant clinical, hormonal, or radiological improvement. Gonadal fu nction was restored in 18 of 27 patients, galactorrhea disappeared in 5 of 6 women, and headache improved in 7 of 8 patients. A significant tumor shrinkage was detected by computed tomography and/or magnetic re sonance imaging in 9 macroprolactinomas and 4 microprolactinomas. CAB was well tolerated by all patients, except 6 who referred slight and s hort-lasting nausea, postural hypotension, abdominal pain, dizziness, and sleepiness at the beginning of treatment. In particular, CAB was w ell tolerated by 19 patients previously shown to be poorly tolerant to BRC and CV 205-502. In conclusion, CAB may represent, at the moment, the only successful therapy for prolactinoma-bearing patients resistan t to BRC and CV 205-502, as it normalized PRL levels in 22 of 27 patie nts, reduced tumor size in 13 of 27 patients, and improved clinical sy mptoms in 25 of 27 patients in the present study.