PURPOSE Dopamine agonist (DA) therapy is recommended as the first-line treatment for prolactinomas. However, it requires long treatment duration, and a high recurrence rate after DA withdrawal has been reported. We aimed to elucidate the predictors for long-term remission following DA withdrawal and propose the best candidates who can achieve complete remission after DA withdrawal.

METHODS In a retrospective cohort study, we included 89 patients with prolactinoma who have withdrawn DAs with normal prolactin (PRL) levels at Seoul National University Hospital, from 2000 to 2016. Patient's data were retrieved from the electronic medical records.

RESULTS The median age and median treatment duration of the study patients were 33 (15-73) years and 69.5 (8.3-277.4) months, respectively. The recurrence rate after drug withdrawal was 57.3% during the 23.9 (3.0-176.8) month follow-up period. Age, gender, baseline PRL level, and baseline maximum tumor diameter were similar between the remission and recurrence group. In the Cox-proportional hazard model analysis, the significant predictors for remission were nadir PRL level of <1 ng/dL (hazard ratio [95% confidence interval] = 0.37 [0.18-0.74]), invisible tumors on magnetic resonance imaging (MRI) (0.42 [0.24-0.74]), and treatment duration of >72 months (0.54 [0.30-0.96]). Of the subjects who met all the three criteria, 66.7% achieved long-term remission.

CONCLUSIONS Patients who have no tumor visible on MRI, have a nadir PRL level <1 ng/dL during drug treatment, and received drug treatment for >6 years may be the best candidates for DA withdrawal.