MON-319 Impact of Tumor Characteristics and Preoperative IGF-1 Levels on Postoperative Hormonal Remission Following Endoscopic Transsphenoidal Surgery in Patients with Acromegaly: A Single-Surgeon Series

Abstract

Introduction:Acromegaly is a potentially fatal neuro-endocrinopathy caused by a growth hormone (GH)-secreting pituitary adenoma (PA). A lack of consensus on factors that reliably predict patient outcomes in acromegalic patients following endoscopic endonasal approaches (EEA) warrants additional investigation.Methods:Pre- and postoperative tumor and endocrinological characteristics from 55 acromegalic patients who underwent EEA for resection of a GH-secreting PA were evaluated as potential predictors of postoperative hormonal remission (defined as age- and sex- normalized IGF-1 levels).Results:The 55 patients included had a mean age of 50.1 ± 13.5 years and a mean follow-up time of 18 ± 17.4 months. Fifty-three patients (96%) presented with dysmorphic craniofacial features, with 22 (40%) presenting with prognathism, 22 (40%) exhibiting frontal bossing, and 18 (33%) presenting with macroglossia. Ten (18%) had microadenomas and 45 (82%) had macroadenomas. Five (9.4%) had giant adenomas. Forty-five (92%) tumors were invasive, with 44 (83%) exhibiting infrasellar invasion, 17 (32%) extending above the sella, and 9 (18%) with cavernous sinus invasion. Thirty-three patients (66%) underwent gross total resection (GTR; mean maximal tumor diameter = 1.52 cm), and 17 (34%) underwent subtotal resection (STR; mean maximal tumor diameter = 2.77 cm). Invasive tumors were significantly larger and Knosp scores were negatively correlated with GTR. Thirty-three patients (65%) achieved hormonal remission after EEA resection alone, which increased to 80% with adjunctive medical therapy. Additionally, 90% of patients who underwent GTR and 63% of patients who underwent STR demonstrated postoperative remission. Six patients (11%) exhibited biochemical remission after postoperative medical therapy with an average time to remission of 5.2 months. These patients all had significantly higher preoperative IGF-1 levels and larger tumors than patients who remitted immediately postoperatively. In all patients preoperative IGF-1 levels were inversely correlated with hormonal remission.Conclusions:This study indicates that endoscopic transsphenoidal resection of growth hormone secreting pituitary adenomas is a safe and highly effective management strategy for achieving hormonal remission and tumor control for patients with acromegaly. When combined with postoperative medical therapy, we observed endocrinological remission rates of 80% based on normalized IGF-1 levels. Our results support the conclusions of current literature that smaller and less invasive tumors are more likely to be fully resected. We additionally suggest that patients with lower preoperative IGF-1 are more likely to undergo postoperative biochemical remission, irrespective of tumor size and invasion.