[Impact of cabergoline on fibrosis in prolactinoma]

Dopamine agonists are an effective and safe treatment for prolactinomas. However, analysis of recent data has shown that dopamine agonists, including cabergoline, can cause tumor fibrosis and complicate subsequent surgery.

To determine the presence or absence of prolactinoma fibrosis in patients receiving cabergoline before surgery and to evaluate its impact on postoperative outcomes.

The study included 58 patients with prolactinoma and preoperative cabergoline therapy who underwent transsphenoidal adenomectomy between January 2018 and March 2025. To identify fibrosis, we analyzed prolactinoma tissue samples regarding connective tissue using Masson's trichrome staining.

Fibrosis in prolactinoma was detected in 18 (31%) patients who received cabergoline. Comparison of patients with prolactinoma fibrosis (group 1, 18 patients) with patients whose prolactinomas did not show fibrosis (group 2, 40 patients) revealed significant differences regarding treatment duration and cabergoline dose (76 vs. 17 months, p<0.001; 3.25 mg/week vs. 2 mg/week, respectively, p=0.049). Resection of fibrous prolactinoma required more time (median 30 min) than non-fibrous prolactinoma (20 min) (p=0.04). The total number of complications was higher in patients with prolactinoma fibrosis (p=0.041).

Treatment of prolactinoma with cabergoline can lead to fibrosis, and appropriate probability is associated with duration of preoperative therapy. Cabergoline-induced fibrosis increased duration of resection and number of complications.