Extent of Resection in Glioblastoma.

The article by Nam and de Groot provides a good overview of treatment options and considerations forglioblastoma. Surgery is a critical mainstay providing diagnostic and therapeutic benefits. The importance of extent of resection for glioblastoma has been debated for decades. Not only important at diagnosis, the relevanceof extent of resection at recurrence is increasing as patients with glioblastoma are surviving longer. After surgery, the neuro-oncologist or medical oncologist may be the sole provider obtaining follow-up imaging. At the time of recurrence or progression, it is crucial to identify patientswhomaybenefit from another resection and obtain neurosurgical evaluation. It is established that maximal safe resection should be performed if benefits outweigh risks and patient wishes are congruent with this approach. Gross total resection is the desired goal for benefit in survivaltimes.Thedogmaticall-or-nothing philosophy for resection is something to reconsider, however. Growing data support varying degrees of subtotal resection for graduatedbenefits insurvival times.Another benefit of resection, either gross total resectionor subtotal resection, is theacquisition of tissue for molecular testing. This is of utmost importance as we continue to elucidate factors affecting prognosis and responsiveness to therapies and develop personalized treatment plans. The definition ofmaximal safe resection becomes individual for each patient as variables are considered in determining the safest operative approach (biopsy, varied degrees of subtotal resection, or gross total resection) for each patient. Whether repeat resection benefits patients is not entirely clear as a result of conflicting studies, most often performed retrospectively, based on differing surgical indications in relatively heterogeneous populations who then receive varied adjuvant therapies. In addition, the extent of resection is often not quantified, the definitions of gross total resection and subtotal resection vary, and all resections may be grouped in comparison with biopsy, further adding to our uncertainty as to the significance of resection in this setting. The majority of both retrospective and prospective data since the turn of the century have favored repeat resection. Focusing on studies done within the era of temozolomide, Bloch et al performed a retrospective review of 107 patients undergoing reresection for glioblastoma and found that gross total resection (. 95%) increased overall survival at salvage surgery for patients who initially had subtotal resection. Karnofsky performance status and extent of resection at progression independently predicted survival. The SN1 study group reported on 503 patients from 20 institutions and found that the extent of resection at recurrence, Karnofsky performance status, and adjuvant therapy after resection increased overall survival. Investigators matched a cohort of 71 patients receiving reresection with patients who did not undergo resection from the prospective Dose-Intensified Rechallenge With Temozolomide (DIRECTOR) trial, wherein patients were randomly assigned to one of two dose-intensified schedules of temozolomide. Overall, surgery did not improve survival, but within the resection cohort, patients with 100% resection of all enhancing tumor had a 6.4-month improvement in postrecurrence survival (P, .001).