Gamma knife radiosurgery for prolactinomas

Object. In this retrospective investigation the authors examined the result s of gamma knife radiosurgery (GKS) for tumor remnants after unsuccessful o pen surgery and medical treatment in 20 patients with prolactinomas. Partic ular attention is paid to a possible radioprotective action of dopamine ago nists similar to the action of octreotide in acromegaly. Methods. Twenty patients with prolactinomas were followed after GKS. Five p atients were treated successfully; their prolactin (PRL) levels dropped int o the normal range and dopaminergic drugs could be discontinued. Two sponta neous pregnancies were observed and 11 patients experienced improvement. Im provement was defined as normal PRL levels with the continued possibility o f reduced medical treatment or a substantially reduced medical treatment do se with some degree of hyperprolactinemia maintained. The treatment failed in three patients who experienced no improvement. Patients treated with dop aminergic drugs during GKS did significantly less well in comparison with t he untreated group when a cumulative distribution function (Kaplan-Meier es timate) was used. Conclusions. The results of GKS for prolactinomas in this investigation are better than the results published by others. This may be an effect of case selection because there were no "salvage cases" in our group of patients. Because a dopamine agonist seemed to induce radioprotection in this series, it is suggested that GKS be performed during an intermission in drug thera py when the dopamine agonist is discontinued.