SUN-448 Giant Prolactinomas: A Follow-Up of 25 Years with Dopamine Agonists

Giant prolactinomas are tumors with a large size > 4 cm and/or prolactin levels higher than 3000 ng/ml and/or highly invasive growth. Today dopamine agonists, mainly cabergoline (CAB), are the first-line choice in the treatment of these tumors. Objective: To assess the efficacy, safety and long-term follow-up of patients with giant prolactinomas treated with dopamine agonists. Methods: We retrospectively reviewed the clinical records of 20 patients with giant prolactinomas. Mean age at diagnosis was: 45.2 ± 18.9 years, 75% men. The median follow-up time was 9.05 years (1.5-25.1). At diagnosis the median prolactin level was 6,545 ng/ml (3,238-15,325), the mean maximum diameter of the tumors was 4.60 ± 1.35 cm. At diagnosis, headaches were present in 55% and hypogonadism in 85% of patients; 80% had invasive tumors and 75% had visual field (VF) impairment. Since the diagnosis, almost all patients were treated with CAB except 2, one with bromocriptine LAR and the other one with oral bromocriptine, both were switched to CAB afterwards. Results: Seventy percent of patients normalized prolactin levels, this was achieved in a median time of 7.5 months (2-26) and with a mean dose 2.14 ±1.19 mg/week of CAB. Fifty-four percent of patients reached this prolactin nadir in 2-4 months with a maximum dose < 2 mg/week. The median prolactin level in the last visit was 31.23 ng/ml (12-147). Ninety percent of patients decreased prolactin level during follow-up: 50% normalized prolactin, 25% remained with a mild hyperprolactinemia, 25% with significant hyperprolactinemia. Ninety-five percent of tumors reduced their volume, 60% evolved to empty sella, the remaining achieved a mean decrease of 3.75 cm compared to the initial size (82% of average reduction compared to the initial diameter). The VF remained normal in patients in whom it was not affected, except in 1 whose VF deteriorated because of chiasmatic ptosis; in the patients who presented VF involvement: 47% improved, 40% remained unchanged and 13% worsened. The complications during the follow-up were: Cerebrospinal fluid leak in 2 patients, chiasmatic ptosis in 1 with VF impairment, intra-tumoral hemorrhage in 1. In the follow-up only 1 patient required surgery; 4 patients died, 2 because of the tumor. In 3 (15%) patients CAB was stopped at 96-180-264 months after treatment was initiated, but in all of them CAB was reinitiated due to symptomatic hyperprolactinemia. In 16 patients the treatment could never be discontinued. Conclusions: CAB was effective in the treatment of giant prolactinomas reducing tumor size (some of them evolved to empty sella) and prolactin levels in most patients, with low-moderate doses of CAB and very few complications. In our experience of 25 years of follow-up, we have not had any patients without treatment.