Gross Total Resection in Low-Grade and Pretreated High-Grade Invasive Growth Hormone Pituitary Adenomas Promises Favorable Outcomes

Introduction: Growth hormone (GH)-secreting pituitary tumors produce systemic comorbidities, thus achieving gross total resection (GTR) and biochemical remission are imperative. The aim of this study was to identify predictors affecting resection status and biochemical remission. Methods: We retrospectively reviewed 54 GH adenoma patients receiving endoscopic endonasal transsphenoidal approach (EETSA). Medical records and magnetic resonance imaging were reviewed for tumor size, volume, resection status, invasion status, and Knosp and Hardy-Wilson grades. We also classified invasion status into high- and low-grade groups. Biochemical remission was defined as an insulin-like growth factor 1 value within sex- and age-adjusted reference or a random GH level < 1.0 ng/mL. Results: The degrees of horizontal and vertical invasion based on preoperative Knosp and Hardy-Wilson grade were highly associated with intraoperative resection status (p=0.015, 0.014 and 0.017 respectively). We also found more significant differences between resection status and higher-grade invasion (p=0.006, 0.006 and 0.001, respectively). Knosp, Hardy-Wilson grades and resection status were significantly associated with biochemical remission (p=0.0007, 0.0428, 0.0006 and 0.0012, respectively). Although there was no difference between micro- or macroadenoma, tumor size and volume were statistically significant associated with outcomes (p=0.024, 0.0032, respectively). Similarly, more significant differences between biochemical remission and higher-grade invasion were found (p=0.00005, 0.009 and 0.00001, respectively). Conclusions: EETSA remains the best treatment option for GH adenomas. Biochemical remission was highly associated with invasion status and the possibility of achieving GTR. Earlier diagnosis and more aggressive resection for low-grade and pretreated high-grade tumors are the key factors associated with favorable outcomes.