Endocrine Abstracts

Objective: Prospective study of cabergoline effect in newly diagnosed patients with giant invasive prolactinomas.

Patients and methods: The study group included 121 patients with giant prolactinomas (tumors larger than 40 mm in size); among them 49 patients had tumors larger than 60 mm in size. 91 male and 30 female aged 16–67 years (median 37) were treated with 0.5–3.5 mg/week (mean 1.5 mg) cabergoline. The treatment period was 6–120 months (median 18).

Results: Before treatment 117 (97%) patients had hypogonadism, 99 (82%) - visual impairments, 71 (59%) - headaches, 29 (24%) - epileptic syndrome. Serum prolactin level before treatment ranged between 12990 and 2210000 mU/l (median 198000; normal 30–545 mU/l). Decrease of prolactin occurred in 114 (94%) patients; prolactin level was normalized during treatment in 49% of cases; 98/121 (81%) patients had significant adenoma shrinkage; 77/99 (78%) patients with pre-treatment visual abnormalities had visual improvement, 67/71 (95%) - headache regression. In 17 patients cerebrospinal fluid (CSF) leakage occurred within 3–6 weeks, in 1 case - in 76 months after initiation of treatment. In 15 patients endoscopic endonasal surgery for fistula repair was performed; in two patients the CSF leakage ceased after diuretic therapy and temporarily cabergoline dosage decrease; 7 (6%) patients had rapid progression cabergoline-resistant tumors. They had surgery followed by stereotactic radiotherapy. PRL-secreting pituitary carcinomas with intra- and extracranial metastases were diagnosed in three cases; 5 (4%) patients showed tumor enlargement due to intratumoral hemorrhage.

Conclusion: Cabergoline should be the first-line therapy for giant invasive prolactinomas. Use of cabergoline results in effective reduction of prolactin, improvement of visual defects and provides tumor shrinkage. However, patients with giant prolactinomas are at a risk of CSF leakage and tumor enlargement during primary cabergoline treatment.