Early Prediction of Long-Term Response to Cabergoline in Patients with Macroprolactinomas

BackgroundCabergoline is typically effective for treating prolactinomas; however, some patients display cabergoline resistance, and the early characteristics of these patients remain unclear. We analyzed early indicators predicting long-term response to cabergoline.MethodsWe retrospectively reviewed the cases of 44 patients with macroprolactinomas who received cabergoline as first-line treatment; the patients were followed for a median of 16 months. The influence of various clinical parameters on outcomes was evaluated.ResultsForty patients (90.9%) were treated medically and displayed tumor volume reduction (TVR) of 74.7%, a prolactin normalization (NP) rate of 81.8%, and a complete response (CR; TVR >50% with NP, without surgery) rate of 70.5%. Most patients (93.1%) with TVR ≥25% and NP at 3 months eventually achieved CR, whereas only 50% of patients with TVR ≥25% without NP and no patients with TVR 25% at 3 months without NP, particularly those with huge prolactinomas, because a delayed response may be achieved. As surgery can reduce the cabergoline dose necessary for successful disease control, it should be considered for cabergoline-resistant patients.