Endocrine Abstracts

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 (DA), mainly cabergoline (CAB), are the first-line choice in the treatment of these tumors

To assess the efficacy, safety and long-term follow-up of patients with giant prolactinomas treated with DA. We retrospectively reviewed the clinical records of 33 patients with giant prolactinomas. Mean age at diagnosis was 39.5 ± 18.5 years, 73% men. The median follow-up time was 6.6 years (2.5 – 9.6). At diagnosis, median prolactin (PRL) level was 4.700 ng/ml (3.131 – 10.900), mean maximum diameter of the tumors was 4.77 ± 1.15 cm; headaches were present in 58%, hypogonadism in 79%; 85% had invasive tumors, 82% had visual field (VF) impairment. Since diagnosis, almost all patients were treated with CAB except 2, who were started on bromocriptine, both were switched to CAB afterwards. Results: 64% of patients normalized PRL levels (median time of 6 months) with a mean dose of 1.66 ± 1.49 mg/week of CAB. Fifty-three percent of patients reached this prolactin nadir in 2 – 4 months with a maximum dose < 2 mg/week. Median PRL level in the last visit: 34.78 ng/ml. Ninety-four percent of patients decreased PRL level during follow-up: 48% normalized PRL, 13% remained with mild hyperprolactinemia, 39% with significant hyperprolactinemia. Eighty-five percent of tumors reduced volume, 36% evolved to empty sella, the remaining tumors achieved a mean decrease 1.48 cm compared to initial size (69% average reduction compared to the initial diameter). VF remained normal in patients in whom it was not affected, in the patients who presented VF involvement: 42% improved, 49% remained unchanged, 9% worsened. Complications during follow-up: Cerebrospinal fluid leak 3 patients, chiasmatic ptosis 1, intra-tumoral hemorrhage 1. In follow-up, 5 patients required surgery; 5 patients died, 3 because of the tumor. In 4 patients CAB was stopped between 48–264 months after initiating treatment, but in all of them CAB was reinitiated due to symptomatic hyperprolactinemia, in 28 patients treatment was never discontinued.

Conclusions: With low-moderate does of CAB and very few complications, CAB was effective in treatment of giant prolactinomas reducing tumor size (some of them evolved to empty sella) and normalizing PRL levels in almost half of our patients. In our experience of 25 years of follow-up we have not had any patients without treatment.