Dynamic integrated response to dopamine agonist monotherapy in Chinese men with prolactinoma: a retrospective cohort study

Male prolactinoma is frequently characterized by delayed diagnosis, greater tumor burden, and more severe endocrine dysfunction. Treatment success is still often assessed using single endpoints, although prolactin (PRL) control, tumor shrinkage, and gonadal-axis recovery may be discordant. To evaluate real-world follow-up outcomes of dopamine agonist (DA) monotherapy in male prolactinoma, develop an integrated response framework, and identify baseline and stage-specific dynamic markers associated with final response. We retrospectively analyzed 108 men with prolactinoma who received DA monotherapy and were followed for more than 1 year at a single tertiary center. Patients had undergone or received surgery and/or radiotherapy during follow-up were excluded. Final response was classified by integrating PRL normalization and tumor-volume reduction: good response (normal PRL plus tumor-volume reduction > = 50%), partial response (discordant response, comprising either normal PRL with tumor-volume reduction < 50% or elevated PRL with tumor-volume reduction > = 50%), and poor response (elevated PRL plus tumor-volume reduction < 50%). Baseline, 3-month, and 1-year variables were assessed using group comparisons, stage-specific logistic regression, receiver-operating-characteristic analysis, bootstrap internal validation, and sensitivity analyses. The mean age at diagnosis was 41.8 +/- 14.7 years. The median baseline PRL was 1039.00 (321.50–4700.00) ng/mL and the median baseline tumor volume was 2710.50 (435.00-8782.50) mm 3 . 25 patients (23.1%) had microadenomas and 83 (76.9%) had macroadenomas. Over a mean follow-up of 2.84 +/- 1.55 years, PRL normalization was achieved in 75 patients (69.4%), PRL normalization plus testosterone recovery in 59 (54.6%), and tumor-volume reduction > = 50% in 86 (79.6%). At the last follow-up, 61 patients (56.5%) had a good response, 39 (36.1%) had a partial response, and 8 (7.4%) had a poor response. Lower baseline BMI was associated with final good response (OR 0.810, 95% CI 0.690–0.950; P = 0.010), as was greater 3-month PRL reduction (OR 3.093 per 10% increase, 95% CI 1.301–7.349; P = 0.011). At 1 year, PRL normalization (OR 17.712, 95% CI 4.538–69.134; P < 0.001) and greater tumor-volume reduction (OR 1.106 per 10% increase, 95% CI 1.005–1.217; P = 0.039) were independently associated with final good response. ROC analysis showed better discrimination for dynamic markers with exploratory cutoffs of PRL reduction > = 0.948 at 3 months and PRL < = 23.30 ng/mL at 1 year. Complete tumor disappearance occurred in 10 patients and was more frequent in microadenomas than in macroadenomas (28.0% vs. 3.6%; P = 0.001). DA monotherapy achieved high rates of biochemical and structural control across tumor-size groups in male prolactinoma, but discordant outcomes were common. An integrated, time-dependent response framework may refine follow-up stratification, distinguish transitional from persistent partial responses, and provide a candidate endpoint framework for future validation studies. Not applicable.