Plasma Matrix Metalloproteinase-9 Predicts Intraoperative Experience and Extent of Resection in Vestibular Schwannoma Surgery.

OBJECTIVE: To evaluate the predictive value of plasma matrix metalloproteinase-9 (MMP-9) level in determining the extent of tumor resection (EOR) and tumor adherence in vestibular schwannoma (VS) surgery. STUDY DESIGN: Prospective cohort study. SETTING: Academic referral center. METHODS: Plasma and tumor samples were prospectively collected from patients with nonradiated, sporadic VS undergoing microsurgical resection from July 2022 to June 2023. Plasma MMP-9 levels were measured by enzyme-linked immunosorbent assay, and their association with tumor adherence and postoperative outcomes were evaluated. RESULTS: Thirty-three patients undergoing microsurgical resection agreed to participate (15 females, median age 54 years old, median tumor size 26.7 mm). A gross total resection (GTR) was performed in 18 patients (55%), and a near-total (NTR)/subtotal resection (STR) in 15 (45%). Tumor size was not significantly different between the GTR and NTR/STR groups (20.7 vs 24.8 mm, P= .185). Intraoperatively, a larger fraction of NTR/STR tumors were highly adherent to the brainstem and/or cranial nerves (93% vs 56%, P = .015). Preoperative plasma MMP-9 was higher in patients who underwent an NTR/STR compared to a GTR (229.9 vs 131.2ng/mL, P = .007). On multivariable logistic regression, preoperative plasma MMP-9 strongly predicted EOR by receiver operating characteristic analysis (area under the curve [AUC] = 0.77 P = .008). Combining plasma MMP-9 and age was an excellent predictor of EOR (AUC = 0.91, P = .0001). CONCLUSION: Plasma MMP-9 levels strongly predicted intraoperative tumor adherence and postoperative extent of resection. This could provide crucial preoperative insights into surgical difficulty, potential complications, and the likelihood of gross total tumor removal, enhancing informed decision-making for both physicians/surgeons and patients.