Operability of Glioblastomas
While surgery is the standard initial approach for glioblastoma, the question of what percentage are "operable" is misleading—virtually all glioblastomas can undergo some form of surgical intervention (biopsy, partial resection, or attempted gross total resection), but true complete removal is biologically impossible due to their infiltrative nature. 1, 2
The Reality of Glioblastoma Surgery
Why Complete Resection is Impossible
Glioblastomas diffusely infiltrate surrounding brain tissue and frequently cross the midline to involve the contralateral hemisphere, making it impossible to distinguish tumor margins from normal brain during surgery. 1, 2
Tumor cells extend well beyond the contrast-enhancing portion visible on MRI, infiltrating into the peritumoral edema seen on T2-weighted imaging, which means the true tumor extent cannot be visualized or safely removed. 1, 2
Current imaging techniques fundamentally underestimate tumor extent because contrast enhancement reflects blood-brain barrier disruption rather than actual tumor boundaries. 1, 2
Surgical Approach Distribution in Practice
Based on contemporary data, when glioblastoma patients undergo surgery:
Approximately 35-41% achieve gross total resection (GTR) of the contrast-enhancing portion only, not true complete removal. 3
The remaining 59-65% undergo subtotal resection, partial resection, or biopsy due to tumor location near eloquent cortex, crossing of midline, or involvement of deep structures. 1, 4
In multifocal glioblastoma specifically, only 15% achieve GTR, 14% subtotal resection, 32% partial resection, and 39% require biopsy only. 4
Clinical Decision-Making for Surgical Candidacy
When Maximal Safe Resection Should Be Attempted
Surgery is recommended as the initial therapeutic approach for obtaining tissue diagnosis, alleviating mass effect, and improving survival when feasible. 1
Maximal safe resection should be the goal while preserving neurological function, as extent of resection ≥98% of contrast-enhancing tumor is associated with significantly improved survival (median 14 months vs 9 months for <98% resection). 3
Age <65 years and good performance status (KPS ≥70) are associated with better surgical outcomes and should favor aggressive resection attempts. 1, 3
When Only Biopsy is Appropriate
Tumors in eloquent cortex, deep structures, or crossing midline where aggressive resection would cause unacceptable neurological deficits. 1
Poor performance status or medical comorbidities that preclude safe anesthesia or recovery from craniotomy. 1
Multifocal disease with multiple separate lesions where resection of all sites is not feasible—though even here, resection of dominant lesions may provide survival benefit over biopsy alone. 4
Survival Impact of Surgical Extent
GTR (≥98% resection) provides median survival of 14-17 months compared to 9-11 months for subtotal resection and 5-7 months for biopsy only. 3, 4
Even subtotal and partial resections provide survival advantage over biopsy in multivariate analysis controlling for age, performance status, and adjuvant therapy. 4, 5
The survival benefit persists even in the modern era with temozolomide and radiation, suggesting surgery remains crucial despite improved adjuvant therapies. 5
Critical Caveat
The term "operable" is clinically imprecise for glioblastoma—the relevant question is not whether surgery can be performed (it almost always can in some form), but rather what extent of safe resection is achievable without causing devastating neurological deficits. 1, 2 The goal should always be maximal safe resection of contrast-enhancing tumor, recognizing that microscopic infiltrative disease will inevitably remain and require adjuvant therapy. 1