Endocrine Abstracts

Introduction: Trans-sphenoidal Surgery (TSS) remains the primary treatment for acromegaly in most patients, but no previous data exist on outcomes for patients treated with gamma knife radiosurgery (STRS) as a primary treatment.

Methods: 20 patients with acromegaly underwent primary STRS at the National Centre for Radiosurgery, Sheffield, UK between 1985 and 2015. Data collection: note review, database, laboratory results, patient questionnaire, and death certification. Guideline-based Biochemical control was defined as normal age-sex-adjusted IGF1 levels and either GH<0.3 μg/l (OGTT) or random GH<1 μg/l or mean Growth Hormone Day Curve (GHDC) <1 μg/l. Pragmatic remission was defined as any one of the above criteria.

Results: Of 12 patients taking acromegaly-specific medication all had ‘guideline-based’ control at 20 years (n=9; 3 deaths), with median time to control being 3 years. Median time to guideline-based control off medication was 7.4 years, with 75% achieving this at 20 years (3/4; 3 deaths; 5 censored). Using ‘pragmatic remission’, all patients achieved biochemical control on acromegaly-specific medication at a median of 3 years (n=19; 1 death). 72% achieved control off medication (n=7), with 25% achieving this by 3 years. Median marginal radiation dose was 27.5 Gy and median follow-up was 166.5 months. Seven patients died at a median age of 65 years. There were no STRS-related deaths. 53% of patients developed new hypopituitarism at a median follow-up of 146 months, with first onset of hypopituitarism as late as 20 years after treatment. No other complications were noted. 3 patients underwent subsequent TSS due to poor biochemical control.

Conclusion: This is the first report to selectively analyse patients who have undergone primary STRS for acromegaly, and shows low morbidity, but significant latency to biochemical control and new onset hypopituitarism mandating very long-term follow-up for all patients who have undergone gamma knife treatment for acromegaly.