Introduction: There is limited information on MGMT status, extent of surgical resection and its impact on overall outcomes in patients undergoing surgery for Glioblastoma.
Methods: Following IRB approval, 233 newly diagnosed GBM patients with known MGMT status treated at Cleveland Clinic (2009-2015) were included in our analysis. Clinical, imaging and follow up data were collected from the database. OS and progression free survival (PFS) from the date of pathological diagnosis were primary and secondary end points respectively. Cox proportional hazard models were used for analysis.
Results: 51.9% of patients were less than 65 years of age and 44.2% were MGMT positive. Median residual tumor volume was 1.1 cc and extent of complete resection of enhancing tumor on imaging was 96% (range 26%- 100%). 83.1% of patients had KPS = 70. Estimated median overall survival and progression free survival was 10.9 months (95%CI = 8.4, 13.2) and 5.4 months (95%CI = 4.6, 6.1) respectively. Overall, extent of resection (= 86%), KPS (= 70), and concurrent chemo radiation therapy were independent predictors of both OS and PFS. MGMT status was an independent predictor of PFS (HR: 0.52, p=0.005) but only marginally associated with OS (p=0.059). In MGMT methylated patients, extent of resection(= 86%) and good performance status (KPS= 70) were independently associated with PFS and OS respectively (PFS: HR: 0.21, p=0.015; OS: HR: 0.05, p=0.002). In MGMT negative patients, extent of resection (= 86%) was independently associated with OS (p=0.039). Concurrent chemo radiotherapy was associated with OS/PFS irrespective of age and MGMT status.
Conclusions: Greater extent of resection of enhancing tumor was associated with improved PFS in MGMT positive patients, OS in MGMT negative patients and OS regardless of MGMT status. Elderly patients with positive MGMT status was found to have improved PFS whereas younger patients have improved OS with MGMT positive status.
Patient Care: Results of our research can be considered while planning the surgical resection as well as prognosticating patients with newly diagnosed GBM following surgical resection.
Learning Objectives: By the conclusion of this session, participants should be able to:
1) Understand the correlation between extent of tumor resection and MGMT status in patients with newly diagnosed GBM.