Prolactinoma - which patients react favorably to cabergoline medication?

Objective. Prolactinoma, as a common endocrine disorder and the most frequent type of pituitary tumor, acts primarily as a suppressor on the gonadal functions. It is generally successfully treated with dopamine agonists; however, treatment resistance still remains in an unneglectable ratio. In this study, we aimed to identify factors, which may play a role in the treatment response. Methods. Seventy-six patients with prolactinoma, who have been routinely followed between 2018 and 2022 in Istanbul Research and Educational Hospital Endocrinology Outpatient Clinic, were included into the study. Initial prolactin level, adenoma size, baseline weight, body mass index (BMI), glucose, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, and triglyceride levels were obtained from the patient's medical records. The patients were divided into two groups: treatment respondent and non-respondent (refractory) ones, according to treatment response in the duration as suggested by the guidelines. The treatment respondent and non-respondent groups were compared according to the initial and the 3rd month prolactin levels, adenoma size, weight, BMI, and metabolic values. Results. The initial tumor diameter was 15.27±10.62 mm in the refractory and 7.42±4.42 mm in the treatment respondent groups (p=0.01). The refractory group had higher prolactin baseline level 269.96±275.78 µg/l vs. 124.55±67.35 µg/l of the respondent group (p=0.01). The refractory group had higher the 3rd month prolactin level 50.97±52.55 µg/l vs. 29.70±27.31 µg/l of the respondent group (p=0.04). The refractory group had higher frequency of cystic/hemorrhagic adenoma (47.6%, n=11/21) (p=0.01), baseline pituitary failure (33.3%, n=7/21) (p=0.01), and baseline cavernous sinus invasion (25.8, n=5/21) (p=0.01). The treatment respondent group had lower initial body weight (69.54±17.51 kg vs. 83.29±16.21 kg) (p<0.01), and lower BMI (25.98±5.47 kg/m² vs. 27.69±6.42 kg/m²) (p=0.02). Conclusions. In this study, initial tumor size, male gender, weight, BMI, the 3rd month prolactin level, initial pituitary deficiency, and cystic/hemorrhagic component in pituitary imaging in patients with prolactinoma were associated with a lower treatment response.