Stereotactic radiosurgery for acromegaly: an international systematic review and meta-analysis of clinical outcomes

Introduction: We performed a systematic review and meta-analysis of clinical outcomes for patients with acromegaly treated with stereotactic radiosurgery (SRS). Methods: Primary outcomes were 5- and 10-year endocrine remission (ER) and endocrine control (EC). Secondary outcomes were 10-year radiographic local control (LC), visual toxicity, and hypopituitarism rates. Weighted random effects meta-analyses using the DerSimonian and Laird methods were conducted to characterize and compare effect sizes. Mixed effects regression models were used to examine correlations between potential prognostic factors and primary and secondary outcomes. Results: In total, 1533 patients across 20 published studies with acromegaly treated with SRS were included. At 5-years, estimated ER and EC rates were 43.2% (95% CI 31.7–54.6%) and 55.0% (95% CI 27.6–82.4%), respectively. At 10-years, estimated ER and EC rates were 56.9% (95% CI 47.5–66.4%) and 69.7% (95% CI 47.7–91.8%), respectively. The estimated 10-year LC rate was 92.8% (95% CI 83.0–100%). Visual toxicity and hypopituitarism following SRS were estimated to be 2.7% (95% CI 1.3–4.2%) and 26.8% (95% CI 16.9–36.7%), respectively. Every 1 Gy increase in margin prescription dose beyond 17 Gy was estimated to result in a 0.41% increased risk of visual toxicity (p = 0.03). No prognostic factors were associated with EC, ER, LC, or hypopituitarism. Conclusions: SRS was well-tolerated in the management of pituitary acromegaly resulting in gradually improving ER and EC rates over time that approached 60% and 70%. SRS-related visual loss is an uncommon treatment-related side effect, and patient-specific clinical decision making remains critical.