Outcome of stereotactic radiotherapy for patients with uncontrolled acromegaly

Linear accelerator based stereotactic radiation therapy (SRT) has been used for the treatment of pituitary tumours; however, little is known concerning the use of this modality for the treatment of patients with acromegaly. We have prospectively studied the short-term outcome of SRT in 12 acromegaly patients who failed to achieve biochemical remission despite surgery and/or pharmacologic therapy.

We identified all patients who had biochemically uncontrolled acromegaly and were treated with SRT between April 2003 and December 2006. All patients were followed prospectively based on a pre-defined protocol that included Goldman visual field examination, MRI of the sella, and pituitary hormone testing at 3, 6, 12 months, and then yearly.

A total of 12 patients with acromegaly were treated with SRT. There were 9 females and the median age of the group was 50 years. The median follow-up was 28.5 months during which time the mean tumor volume decreased by 40%, the median GH fell from 4.1 microg/L to 1.3 microg/L (p = 0.003) and the median IGF-1 dropped more than half from 545.5 microg/L to 260.5 microg/L (p = 0.002). Four patients achieved normal, while an additional 2 achieved near-normal, IGF-1 levels. One patient was able to discontinue and two were able to reduce their acromegaly medications while maintaining a normal IGF-1. A new pituitary hormonal deficit was found at 24 months in one patient who developed hypoadrenalism requiring corticosteroid replacement.

Based on our early experience, we believe that SRT should be considered in treating patients with uncontrolled acromegaly.