Endocrine Abstracts

JOINT2498

Introduction: Prolactinomas are the most common secretory tumors of the pituitary gland, although their prevalence in individuals under 35 years old is relatively rare. The onset of prolactinomas at a young age, particularly in male patients, may be associated with more aggressive tumor behavior. The objective of this study was to evaluate the clinical characteristics of prolactinomas and assess their response to treatment.

Methods: We retrospectively analyzed all patients under 35 years old diagnosed with prolactinoma from January 2015 to May 2024 and extracted clinical, imaging and biochemical parameters. All patients received DA (dopamine agonist) therapy as the first line of treatment. DA resistance is defined as persistent hyperprolactinemia despite high-dose cabergoline treatment.

Results: The study included 63 patients diagnosed with prolactinoma, with a mean age of 25.54 ±5.89 years at diagnosis; 57.1% were female patients. Among all, 25 patients had microprolactinomas, and 38 had macroprolactinomas. Males had a higher prevalence of macroprolactinomas (68.4%) compared to microprolactinomas (12%). All 9 patients diagnosed with giant prolactinomas, with tumor sizes exceeding 40 mm, were male. Of the patients with microprolactinomas, 12% (all female) exhibited resistance to DA therapy and required doses higher than 2.0 mg of cabergoline per week. In contrast, 55% of patients with macroprolactinomas (84.6% of whom were male) required dose escalation. Additional therapeutic approaches, such as transsphenoidal surgery combined with cabergoline (3 cases), radiotherapy (2 cases), and chemotherapy (Temozolomide) (1 case), were implemented for DA-resistant macroprolactinomas. In two cases, multimodal treatment strategies involving surgery, cabergoline, and/or chemotherapy and radiotherapy were necessary. Genetic testing for mutations in the AIP and MEN1 genes was conducted in 7 patients with high clinical suspicion (e.g., age at diagnosis < 20 years, giant and/or invasive tumor, symptomatic hypercalcemia, and/or adrenocortical tumors). One patient was diagnosed with MEN1 syndrome through genetic testing.

Conclusions: Dopamine agonist treatment as first-line therapy, particularly for macroprolactinomas in young male patients, had limited efficacy in controlling the disease, resulting in a greater need for dose adjustments and additional treatment strategies. Genetic testing, particularly for AIP and MEN1 mutations, is recommended for young patients diagnosed with aggressive prolactinomas, but it should be reserved for those with a high clinical suspicion of underlying genetic syndromes.