gms | German Medical Science

Objective: To evaluate the clinical outcome in patients (pts) with growth hormone producing adenomas (acromegaly) after LINAC-radiosurgery (SRS) or stereotactic radiotherapy (SRT).

Method: From 2000 to 2010, a total of 37 pts with acromegaly were treated either with SRS (<4 ccm, low risk) or with fractionated SRT (>4 ccm, close to optic pathways) using the Novalis system. 7 pts were lost for follow-up, 30 pts were enrolled for the study. 15 pts were male, and 15 were female. The patient’s age ranged from 29 to 74 years (median 59 years). All pts were irradiated after one or more surgeries without endocrinological cure. Toxicities were evaluated with the Common Terminology Criteria for Adverse Events (CTCAE) version 3.0.

Results: Tumor volume ranged from 0.11 to 4.80 ccm for SRS and from 2.50 to 19.40 ccm for SRT. 20 pts (66.6%) were treated with SRS, 10 were treated with SRT (33.3%). The median follow-up period was 6 years (range: 0.5–13 years), and 50% of the pts had a follow-up of 5 years or more. Local control rates were 96% with 80% volumetrically proven tumor shrinkage. 80.9% (17/21) of the pts were cured (remission criteria: normal IGF-1) and in 9.5% (2/21) a relevant reduction was achieved. An endocrinological response is generally achieved within 4 (SRS) and 5 (SRT) years (range: 2–5 years for SRS and 2–10 years for SRT) without clear correlation between tumor volume, fractionation or tumor control rate (shrinkage). A post-SRS/SRT high-grade visual disorder occurred in no pts.

Conclusions: After 10 years of experience, we consider LINAC-SRS or SRT for safe and successful in terms of tumor control and normalization of hormone excess, especially for tumors located close to the optic pathways and large tumors. Rates of endocrine improvement are difficult to predict, an endocrinological response is generally achieved within 5 years.