Single Institution Retrospective Study to Determine Time to First True Progression in MGMT-Methylated Glioblastoma Patients Who Received Standard of Care

Background: MGMT-methylated glioblastomas respond well to temozolomide-based standard of care (Stupp protocol), demonstrate longer survival as compared to unmethylated tumors, and carry an increased risk of pseudo-progression. Establishing time to first true progression can serve as a non-invasive clinical reference point to distinguish true from pseudo-progression. Objective: To define the time to first true progression in patients with MGMT-methylated glioblastoma who were treated with the standard of care/Stupp protocol. Methods: We conducted a retrospective analysis from our institutional database of MGMT-methylated glioblastoma patients from 2018–2024. Time to first progression was measured from initial surgery to first true progression, as determined by a multidisciplinary team based on radiographic imaging review and/or pathology. Results: Fifteen patients met eligibility criteria. Median time to first progression of MGMT-methylated glioblastoma patients who received standard of care was twenty-one months. 40% of patients remained progression-free beyond thirty-six months after their initial surgery. Conclusions: Most patients with MGMT-methylated glioblastomas do not develop true progression within the first year and a half post-operatively. Therefore, MRI changes on surveillance scans should be carefully interpreted within this time frame. Expected timeline for true progression, alongside advanced radiographic imaging techniques and knowledge of treatment-specific pseudo-progression risk, may improve diagnostic accuracy.