Clinical results of LINAC-based stereotactic radiosurgery for pituitary adenoma

PURPOSE: We retrospectively evaluated our clinical results of stereotactic radiosurgery (SRS) for pituitary adenoma. MATERIALS AND METHODS: Between 1995 and 2000, 13 patients were treated with SRS for pituitary adenoma. In all cases, the tumors had already been surgically resected. The adenomas were functional in 5 and non-functional in 8 patients. The median follow-up period was 30 months. SRS was performed with the use of a dedicated stereotactic 10-MV linear accelerator (LINAC). The median dose to the tumor margin was 15 Gy. The dose to the optic apparatus was limited to less than 8 Gy. RESULTS: MR images of 12 patients revealed tumor CR in one case and PR in 9 cases; in the remaining two patients, tumor size decreased by less than 50%. There was no recognizable regrowth of any of the tumors. In two of four GH-secreting adenomas, hormonal overproduction normalized, while the other two showed reduced hormonal production. One PRL-secreting adenoma did not respond. Reduction of visual acuity and field was seen in one patient. This patient also had a brain infarction. None of the patients developed brain radionecrosis or radiation-induced hypopituitarism. CONCLUSION: Although further studies based on greater numbers of cases and longer follow-up periods are needed, our results suggest that SRS seems to be a safe, effective treatment for pituitary adenoma.