Glioblastoma multiforme (GBM) ranks among the most common and fatal types of brain tumors that occur in adults, and the disease is largely characterized by its invasive and aggressive behavior. Various surgical procedures have been somewhat effective for some patients, ranging from minimally invasive biopsy to craniotomy, with the goal being to achieve gross total resection (GTR). Guided intraoperative techniques have increased the extent of resection (EOR) that is surgically possible, but all patients do not receive this aggressive treatment.
“Surgery is a mainstay of therapy in GBM, but we recognize that we can’t achieve clean margin resections in many cases because the brain is so delicate,” explains Michael Glantz, MD. He adds that there is currently no consensus on the optimal EOR that is needed to improve survival. Prior meta-analyses on the subject of EOR and overall survival in GBM have produced contradictory results, and the data suggest that currently available treatment options do little to extend survival. The association between EOR and outcome remains undefined, notwithstanding many relevant studies.
Addressing a Need
Considering that there is widespread treatment variation in GBM, Dr. Glantz and colleagues had a meta-analysis published in JAMA Oncology that examined if GTR— as compared with subtotal resection (STR) or biopsy—could improve overall and progression-free survival. After conducting a systematic review of investigations involving newly-diagnosed GBM patients, the authors identified 37 studies that compared various EOR and presented objective overall or progression-free survival data. This resulted in more than 41,000 unique patients for inclusion.
Findings of the analysis showed that patients with newly diagnosed GBM who received GTR were 61% more likely to survive at 1 year when compared with patients receiving only an STR. GTR recipients were also 19% more likely to survive 2 years, and 51% more likely to be progression free at 12 months when compared with patients receiving only an STR. “The consistency of the evidence supports the superiority of GTR over STR and biopsy, adds Dr. Glantz.
Shifting the Focus
Importantly, Dr. Glantz says that it is unlikely future retrospective cohort trials will contribute additional useful data. “We lack randomized clinical trials (RCTs) in GBM because they aren’t feasible in these patients,” he says. “However, we now have statistical and analytic techniques that can yield results that are almost as valuable as RCTs. We need to work toward developing a high-quality multi-national prospective registry of patients with GBM that includes audited data in its design. This data would provide more value by helping clinicians identify factors that affect patient outcomes. In addition, we should examine practice variation in the management of other lower-grade malignant GBM tumors. Collecting and analyzing this type of data should be a critical priority for the neurosurgical and oncology communities.”
Michael Glantz, MD, has indicated to Physician’s Weekly that he has no financial disclosures to report.