Long-term safety of gamma knife radiosurgery (SRS) for acromegaly.

PURPOSE: Acromegaly has high morbidity and mortality when growth hormone secretion remains uncontrolled. Stereotactic radiosurgery (SRS) may be used when pituitary surgery is not suitable or unsuccessful, but there are few very long-term safety data available, especially for significant adverse events such as stroke. METHODS: 118 patients with acromegaly were treated with SRS between 1985 and 2015, at the National Centre for Stereotactic Radiosurgery, Sheffield, UK. Data were gathered from case notes, hospital databases, and patient questionnaires. Stroke incidence in comparison to the normal population was quantified using the standardised incidence ratio (SIR), and visual complications assessed. RESULTS: 88% (104/118) had complete morbidity follow up data for analysis. The mean follow-up was 134 months, and median SRS dose was 30 Gy. 81% of tumours had cavernous sinus invasion. There was no excess stroke rate relative to that seen in two age- and sex-matched large population studies (SIR = 1.36, 95% CI 0.27-3.96; SIR = 0.52, 95% CI 0.06-1.89). In 68/104 patients who had MRI-guided SRS with no further radiation treatment (SRS or fractionated radiotherapy) there was no loss of visual acuity and 3% developed ophthalmoplegia. There was a positive correlation between > 1 radiation treatment and both ophthalmoplegia and worsening visual acuity. CONCLUSION: Stroke rate is not increased by SRS for acromegaly. Accurate MRI-based treatment planning and single SRS treatment allow the lowest complication rates. More than one radiation treatment (SRS or fractionated radiotherapy) was associated with increased visual complications.

Radiosurgery as primary management for acromegaly.

OBJECTIVE: Transsphenoidal surgery (TSS) remains the recommended primary treatment for acromegaly. Long-term outcome data are not available for patients treated with gamma knife radiosurgery (STRS) as a primary treatment. DESIGN: Retrospective cohort study. DATA COLLECTION: notes review, laboratory results, general physician notes, patient questionnaire and death certification. PATIENTS: Twenty acromegaly patients underwent primary STRS at the National Centre for Radiosurgery, Sheffield, UK, between 1985 and 2015. MEASUREMENTS: Biochemical control (GH/IGF1), hypopituitarism, morbidity and mortality were all recorded. RESULTS: At 20 years of follow-up, control was seen in all on acromegaly-specific medication (n = 12) and 75% of those off medication (3/4). Time for 50% to achieve control on medication was 3 years, and 7.4 years off medication. Median marginal radiation dose was 27.5 Gy, and median follow-up was 166.5 months. 53% of patients developed new hypopituitarism at a median follow-up of 146 months, and the development of first onset of hypopituitarism occurred as late as 20 years after treatment. With MRI planning, no other complications were noted. Three patients underwent subsequent TSS due to poor biochemical control. During follow-up, 7 patients died at a median age of 65 years. There were no STRS-related deaths. CONCLUSION: This is the longest follow-up of patients who have undergone primary STRS for acromegaly. It shows low morbidity, but significant latency to biochemical control and new-onset hypopituitarism. This mandates very long-term follow-up for these patients. STRS has shown good long-term efficacy providing initial control can be afforded by optimal medical management. While TSS remains best practice, STRS offers an alternative for those in whom surgery is not an option.