Long-term cabergoline use does not predict degree of prolactinoma fibrosis nor significantly impact surgical outcomes.

PURPOSE: Prolactinomas are often treated initially with dopamine agonists (DA). For patients subsequently treated with surgery, the effect of cabergoline (CAB) on tumor fibrosis and its potential impact on surgical outcomes is largely unexplored. METHODS: Records of patients with prolactinoma treated by a single surgeon between 2006 and 2024 were examined. Analyses considered relationships among duration and cumulative dose of presurgical DA (DA + vs. DA-), extent of fibrosis measured quantitatively by collagen volume fraction (CVF) and qualitatively by surgeon assessment, and remission status at last follow-up. RESULTS: Of 59 patients, 22 were DA- and 37 were DA+, including 29 treated only with CAB and 8 treated with CAB and bromocriptine. There were 44 macroadenomas, 13 microadenomas, and 2 giant adenomas; 28 had cavernous sinus invasion (Knosp grade 3-4) 52.5% were in remission at last follow-up. Median cumulative CAB dose was 79.3 mg (range, 5.4-6711), used for a median duration of 570 days (range, 16-7830). Neither CAB dose nor duration correlated with CVF (r2 < 0.01, p = NS). Both surgeon fibrosis assessment and CVF were higher in DA + patients, but neither independently predicted remission. Cumulative CAB dose and duration also did not predict remission. On univariable analysis, cavernous sinus invasion (OR 10.3, p < 0.001) and tumor size (OR 6.6, p = 0.02) predicted remission, but in multivariable analysis no single factor remained significant. CONCLUSION: Duration and cumulative dose of presurgical CAB use do not correlate with quantitative measures of tumor fibrosis and do not reliably predict the degree of fibrosis at surgery or the likelihood of surgical remission.