P45 Gamma knife radiosurgery for the primary management of acromegaly

Objectives Report outcome and morbidity data for the treatment of acromegaly with primary stereotactic radiosurgery (STRS). Design Retrospective. Subjects 20 patients with acromegaly who underwent primary STRS at the National Centre for Radiosurgery, Sheffield (UK) between 1985 and 2015. Methods Review of notes, database, laboratory results, patient questionnaire and death certification. Guideline-based control was defined as normal age-sex-adjusted IGF1 levels and either random GH Results Control at 20 years was 100% and 75% on and off medication respectively. Median time to control on medication was 3 years and 7.4 years off medication. Median marginal radiation dose was 27.5 Gray and median follow-up was 167 months. Seven patients died, median age 65 years. There were no STRS-related deaths. 53% of patients developed new hypopituitarism at median follow-up of 146 months. First onset of hypopituitarism occurred up to 20 years after treatment. No other complications were noted. Three patients underwent trans-sphenoidal surgery due to poor biochemical control at a mean of 35 months. Conclusions Morbidity from STRS is low. There is significant latency to biochemical control and new onset hypopituitarism. While primary surgical intervention remains the gold standard in acromegaly, primary STRS results should inform discussions with patients considering non-surgical management.