Lack of survival advantage among re-resected elderly glioblastoma patients: a SEER-Medicare study.

Background: The survival benefit of re-resection for glioblastoma (GBM) remains controversial, owing to the immortal time bias inadequately considered in many studies where re-resection was treated as a fixed, rather than a time-dependent factor. Using the Surveillance, Epidemiology, and End Results-Medicare (SEER-Medicare) database, we assessed treatment patterns for older adults and evaluated the association between re-resection and overall survival (OS), accounting for the timing of re-resection.
Methods: This retrospective cohort study included elderly patients (age ≥66) in the SEER-Medicare linked database diagnosed with GBM between 2006 and 2015 who underwent initial resection. Time-dependent Cox regression was used to assess the association between re-resection and OS, controlling for age, gender, race, poverty level, geographic region, marital status, comorbidities, receipt of radiation + temozolomide, and surgical complications.
Results: Our analysis included 3604 patients with median age 74 (range: 66-96); 54% were men and 94% were white. After initial resection, 44% received radiation + temozolomide and these patients had a lower hazard of death (hazard ratio [HR]: 0.28, 95% confidence interval [CI]: 0.26-0.31, P < .001). In total, 9.5% ( n = 343) underwent re-resection. In multivariable analyses, no survival benefit was seen for patients who underwent re-resection (HR: 1.12, 95% CI: 0.99-1.27, P = .07).
Conclusions: Re-resection rates were low among elderly GBM patients, and no survival advantage was observed for patients who underwent re-resection. However, patients who received standard of care at initial diagnosis had a lower risk of death. Older adults benefit from receiving radiation + temozolomide after initial resection, and future studies should assess the relationship between re-resection and OS taking the time of re-resection into account.
(© The Author(s) 2020. Published by Oxford University Press, the Society for Neuro-Oncology and the European Association of Neuro-Oncology.)