Radiotherapy and Radiosurgery for Hormone Secreting Pituitary Adenomas

In Reply: We thank Sakellaridis and Vasilakis for their interest in our recent paper1 that concluded “there appears to be a differential sensitivity after radiosurgery for hormone secreting pituitary adenomas.” Remission rates are greater for patients with Cushing's disease and acromegaly, whereas radiosurgery is less effective at achieving biochemical remission for patients with prolactinomas.” Clearly the patients having radiosurgery were highly selected from the overall experience at our center for patients with prolactin (PRL) secreting pituitary adenomas. As discussed, the majority of patients respond well to medical therapy and never need to be evaluated for surgical resection, fractionated radiation therapy, or stereotactic radiosurgery. However, all of these patients had failed medical therapy and more than half had persistent PRL elevation despite surgical resection. We noted a significant decrease in the serum PRL for this group, although only 2 of 11 patients (18%) achieved biochemical remission off dopamine agonist therapy. The patients' average prolactin level was reduced from 212 ± 252 ng/mL to 37 ± 29 ng/mL (P =.03). Moreover, 9 of 11 patients (82%) had improved symptoms and were able to discontinue their dopamine agonist therapy. We discussed the possibility that with longer follow-up after radiosurgery a greater percentage of these patients may onto biochemical remission. Of note, the references provided comparing conventional radiation therapy to our results had median follow-up intervals of 8 and 9 years, respectively,2,3 compared to 4 years in our series. Also, in those papers as well as the study of Ma et al,4 a clear definition of biochemical remission was not provided so a fair and honest comparison is not possible. Therefore, in spite of our findings we believe that radiosurgery should still be considered an option for patients with prolactinomas refractory to other treatments. Bruce E. Pollock Rochester, Minnesota