THU063 Somatostatin Analog Neoadjuvant Treatment Before Endoscopic Surgery For Growth-Hormone Producing Pituitary Adenomas Invading The Cavernous Sinus: Case Series, Systematic Literature Review And Meta-analysis

Disclosure: B. Rapoport: None. A. Halstrom: None. A. Kelly: None. M. Roytman: None. J. Lantos: None. D. Phillips: None. R. Ramakrishna: None. T. Schwartz: None. G.A. Dobri: None. Background: Pituitary surgery remains the first line of treatment for acromegaly, yet 35-50% of patients with macroadenomas do not achieve biochemical remission postoperatively. Macroadenomas invading the cavernous sinus (Knosp grades 3 and 4) are particularly refractory to surgical management. Adjuvant therapy with somatostatin analogs in refractory cases is well established, but neoadjuvant use of these agents to consolidate invasive tumors prior to surgery remains controversial. Methods: We retrospectively analyzed our series of 84 consecutive cases of acromegaly treated with endoscopic transsphenoidal pituitary surgery between 2004 and 2020. We have used neoadjuvant pretreatment with somatostatin analogs for adenomas invading the cavernous sinus since 2017. We compared radiographic and long-term biochemical outcomes in the first 10 of these patients with a cohort of historical control patients who underwent resection only. We also performed a systematic review and meta-analysis of studies investigating neoadjuvant use of somatostatin analog therapy prior to transsphenoidal surgery for acromegaly. Results: Neoadjuvant therapy significantly reduced total tumor volume and volume of tumor in the cavernous sinus prior to surgery (mean reductions 30% and 48%, respectively, p<0.01), and was associated with trends toward increased rates of gross total resection and biochemical cure. Of those pretreated with neoadjuvant therapy, 60% were found to be in biochemical remission postoperatively compared to 50% in the control group, P 1. In addition, 70% of those pretreated had a gross total resection compared to 50% of controls, P 0.65. Gross total resection was achieved in all patients with Knosp grade 3 tumors, regardless of pretreatment status, and all of these patients entered biochemical remission. In patients with Knosp grade 4 tumors, gross total resection was achieved in 29% of surgery-only patients and 57% of pretreated patients; biochemical remission was achieved in 14% of surgery-only patients, and 29% of pretreated patients. The differences were not statistically significant. Conclusions: In this series of acromegalic patients with macroadenomas invading the cavernous sinus, neoadjuvant somatostatin analog therapy was associated with a trend toward increased rates of gross total resection and biochemical remission. Of note, those who were not in remission in the pretreatment group had a milder biochemical elevation and required lower-intensity medical therapy postoperatively. The systematic literature review and meta-analysis that we have performed confirm a statistically significant increase in remission rate in patients receiving neoadjuvant therapy. Presentation: Thursday, June 15, 2023