8617 Gender Differences In The Course Of Giant Prolactinomas - Single-Centre Case Series

Abstract Disclosure: M.A. Komisarz-Calik: None. A. Boguslawska: None. K. Ciszek: None. G. Zieliński: None. A. Hubalewska-Dydejczyk: None. A. Gilis-Januszewska: None. Introduction: Giant prolactinomas are the specific subtype of lactotroph PitNET, and are classified, according to their maximum diameter (≥40 mm). They constitute about 3% of prolactinomas. The prevalence is more common in men, however, the differences in the course of the disease between the genders remain unclear. Aim: The purpose of our study was to analyse gender differences in the course of giant prolactinomas. Materials and Methods: We analysed the data of consecutive patients with giant prolactinomas treated in the tertiary clinical center in the years 2022-2023. Results: There were 12 patients with giant prolactinoma (10 men and 2 women).Men and women were of similar age (32 vs 36 years). The maximum dimensions of the pituitary tumour in men were 56x70x67 mm, in women 60x55x55 mm. In all cases, treatment included dopamine agonists (cabergoline in 11 patients (all male patients and one female patient) and bromocriptine in one woman. Combined treatment with temozolomide and pasireotide were implemented in two male patients. In three men (30%) a surgical treatment was performed due to the visual field disturbances and severe headaches. Multiple surgeries were performed in two patients due to recurrence of symptoms and tumour progression (surgery was performed twice, and three times). One male patient received radiotherapy.The most frequent symptoms were associated with insufficiency of the adrenal, thyroid, and gonadal axis (80% vs 50%), visual field deficits (50% vs 50%) and headache (80% vs 0%), respectively in men and women. In men, the most common symptom was hypofunction of the gonadal axis (8 cases - 4 isolated gonadal axis hypofunction and 4 cases - hypofunction of the adrenal, thyroid and gonadal axis). In one woman, hypofunction of the three pituitary axes was present. Serum prolactin was higher in men than in women (6576 - 284232 ulU/ml vs 2000 - 5659 ulU/ml). In total, after treatment, prolactin concentration decreased in 7 cases, 5 men (50%) and 2 women (100%). The decrease in prolactin levels in men was by 80,4-99,9%, while in women it was by 83,9-86,7%. Tumour shrinkage was observed in 7 cases - 6/10 men and 1/2 woman. In men, tumour size was reduced by 27,5-64,4%. Tumour progression was observed in three cases, in 1 case the dimensions were stable. In two cases due to a recent diagnosis, follow-up MRI has not been yet performed. In women, tumour reduction by 99,8% was observed; in second the size of the tumour remained stable. Conclusions: The prevalence of giant prolactinomas is higher in men. The most frequent symptoms in both genders are visual field disturbances. The prevalence of tumour shrinkage is similar in both sexes, however giant prolactinomas require surgery more often in men. Further multicenter projects are needed to study the course of giant prolactinomas and to improve the outcomes of care. Presentation: 6/3/2024