MON-LB080 Change of T2-Weighted Intensity of Prolactinoma as a Predictable Value for Relapse of Hyperprolactinemia after Cabergoline Withdrawal

Background The aim of this study were to assess whether change of T2 weighted signal intensity (T2-WSI) on magnetic resonance imaging (MRI) is associated with complete remission after cabergoline withdrawal in patients with prolactinoma. Methods In a retrospective cohort study, we identified 631 patients with hyperprolactinemia and pituitary adenoma from 2005 to 2018. Of 631 patients, 35 patients who stopped the cabergoline medication were included in final analysis. The patients who maintained the cabergoline treatment for less than 1 year and stopped the medical treatment because of the pregnancy or amenorrhea were excluded in this study. We measured T2-WSI of both adenoma and normal portion of pituitary gland on the initial, 6-month follow up MRI using the Picture Archive Communication System. The patients were divided into 2 groups, based on the maintenance of normal prolactin level or relapse after withdrawal of cabergoline. We compared the T2-WSI of pituitary adenoma corrected by T2-WSI of normal tissue between remission and relapse group. Results Only 20% patients relapsed at 6(3-63) months after drug withdrawal in the 14(5-97) month follow-up period. Age (35.2 vs. 29.9 years), baseline PRL level (195.0 vs. 216.7), nadir PRL level during cabergoline treatment (4.3 vs. 3.2), duration of cabergoline treatment (38.6 vs. 34.3 months), and maximal tumor size (9.0 vs. 7.6mm) were similar between the remission and recurrence group (p > 0.05 for all). In order to see whether the change of T2-WSI between initiation of treatment and six-month follow up was different between recurrence group and remission group, we performed a one by two (signal intensity of both MRI) repeated measures analysis of variance using recurrence as a between-subject factors. Result showed that there were no significant main effect of treatment (F (1,33)=2.491, p=0.124). However, there was a significant difference of T2-WSI by treatment interaction, which means that a treatment effect was different between recur and non-recur groups (F(1,33)=4.783, p=0.036). T2-WSI in remission group was significantly decreased after 6 months of treatment (Z=2.03, singned rank=292, p=0.043), but not in recurrence group (signed rank=9, p=0.469). Conclusions In this study, the change of T2-WSI was associated with relapse of hyperprolactinemia in patients with prolactinoma after withdrawal of cabergoline. Further study is necessary for evaluating the clinical significance of T2-WSI in pituitary tumors. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.