MON-439 Evaluation of Surgical Resection Goal and Its Relationship to the Extent of Resection and Patient Outcomes in 221 Patients following Transsphenoidal Surgery for Nonfunctioning Pituitary Adenomas: Data from the TRANSSPHER Study

Background: Prospective data of the influence of the neurosurgeon’s preoperative goal regarding the extent of tumor resection and patient outcomes are scarce in patients with pituitary adenomas who have undergone transsphenoidal pituitary surgery using modern gland-sparing surgical techniques. Objective: We analyze the relationship between surgical tumor removal goal and patient outcomes in a prospective multicenter study of patients with nonfunctioning pituitary adenomas (ClinicalTrials.gov NCT02357498). Methods: Centrally adjudicated extent of tumor resection (gross total resection [GTR] and subtotal resection [STR]) data were analyzed using standard univariate and multivariable analyses. Results: A total of 221 patients were treated with transsphenoidal surgery at 7 pituitary centers in the United States from February 2015 to June 2017. GTR was accomplished in 148 of 171 (86.5%) patients with planned GTR and 32 of 50 (64.0%) patients with planned STR (P = 0.001). Sensitivity, specificity, positive predictive value, and negative predictive values of GTR goal were 82.2%, 43.9%, 86.5%, and 36.0%, respectively. Knosp grade 0-2, first surgery, and being an experienced neurosurgeon were associated with neurosurgeons choosing GTR as the goal (P < 0.01). However, there was no association between surgical goal and the presence of pituitary hormone deficiencies 6 months after surgery (P = 0.31). There was a trend towards a higher rate of major neurological complications in the STR goal cohort (4/50 patients, 8.0%) compared to the GTR cohort (4/171, 2.3%) (p=0.079). Tumor Knosp grade (P = 0.004) and size (P = 0.001) were stronger predictors of GTR than was surgical goal (P = 0.014). The most common site of detecting residual tumor was the cavernous sinus (29 of 41 patients; 70.1%). Conclusion: This is the first prospective multi-center pituitary surgery study that examined surgical goal regarding extent of tumor resection and associated patient outcomes. We found that surgical goal is not a reliable predictor of actual tumor resection, and a more aggressive surgical goal does not correlate with pituitary gland dysfunction or major neurological complications 6 months after surgery. A better understanding of the ability of neurosurgeons to meet their expectations and of the factors associated with surgical result could improve prognostication and preoperative counseling of the extent of tumor resection, and postoperative functionality of pituitary hormone secretion.