Stereotactic conformal radiotherapy in patients with growth hormone-secreting pituitary adenoma

To evaluate the reduction of hormonal overproduction and side effects as well as survival rates after fractionated stereotactic conformal radiotherapy (FSRT) and radiosurgery in patients with growth hormone (GH)-secreting pituitary adenoma.

Between January 1989 and May 2001, 25 consecutive patients were treated with FSRT (n = 20) or radiosurgery (n = 5) for GH-secreting pituitary adenoma. Nine patients were treated for recurrent disease after primary surgery. One patient had primary radiotherapy because of inoperability, and 15 patients received radiotherapy after subtotal resection due to increased GH level. Median total dose was 52.2 Gy for FSRT and 15 Gy for radiosurgery.

Radiologic local tumor control was 100% after a median follow-up of 59.8 months (range, 20.3-168.2 months). Seventeen patients had stable disease on CT/MRI, and eight showed a reduction of tumor volume on MRI scans. Endocrinologic control was 92% (23 of 25 patients). Two patients had an endocrinologic recurrence 21 and 54 months after FSRT. A normalization of preexisting acromegalic symptoms was seen in 1 patient, 4.5 years after FSRT. GH level normalized in 21 of 25 patients after 26 months median. Five of these patients underwent concurrent Octreotid therapy because of increased insulin-like growth factor I levels. Improvement of visual acuity was seen in 1 patient. New onset of clinically evident hypopituitarism as an adverse reaction of stereotactic radiotherapy was only infrequently observed in this series.

Stereotactic conformal radiotherapy is effective and safe in the treatment of GH-secreting pituitary adenoma to reduce hormonal overproduction and to improve local control. It is an alternative option to surgery especially for patients at high risk of surgical complications due to comorbidity.