Predictors of the response to dopaminergic therapy in patients with prolactinoma

Purpose: Withdrawal of dopamine agonist (DA) therapy in patients with prolactinoma who are controlled by a small dose of medication is recommended by several guidelines. So far, the likelihood of reaching withdrawal conditions based on baseline characteristics remains uncertain. Methods: We retrospectively examined early clinical, radiological, or biochemical features that may predict the likelihood of reaching withdrawal conditions in prolactinoma patients. Data were obtained in a single academic medical center in the United States from patients seen between 2000 and 2018. Using multiple logistic regression, we compared patients who reached withdrawal conditions with those who did not. Results: Of 213 patients, 78 (36.6%) reached withdrawal conditions after at least 2 years of DA treatment. Initial maximal tumor diameter was significantly smaller in those who reached withdrawal conditions than in those who did not. Percent prolactin change at the first check from initiation of DA therapy and parasellar invasiveness were predictors of reaching withdrawal conditions. With constant independent variables, there was a 7% increase in odds for reaching withdrawal conditions for every 1% decrease in percent prolactin change at first check after DA therapy start (P = 0.0000). Parasellar invasion decreased the odds of reaching withdrawal conditions by 84% (P = 0.0000). Conclusions: DA remains a potential life-long treatment modality for most prolactinoma patients. Patients with parasellar invasiveness and low prolactin percent change from baseline to first prolactin check are more likely to require long-term treatment.