Laura A. Snyder, Andrew B. Wolf, Mark E. Oppenlander, Robert Bina, Jeffrey R. Wilson, Lynn Ashby, David Brachman, Stephen W. Coons, Robert F. Spetzler and Nader Sanai
Recent evidence suggests that a greater extent of resection (EOR) extends malignant progression-free survival among patients with low-grade gliomas (LGGs). These studies, however, rely on the combined analysis of oligodendrogliomas, astrocytomas, and mixed oligoastrocytomas—3 histological subtypes with distinct genetic and molecular compositions. To assess the value of EOR in a homogeneous LGG patient population and delineate its impact on LGG transformation, the authors examined its effect on newly diagnosed supratentorial oligodendrogliomas.
The authors identified 93 newly diagnosed adult patients with WHO Grade II oligodendrogliomas treated with microsurgical resection at Barrow Neurological Institute. Clinical, laboratory, and radiographic data were collected retrospectively, including 1p/19q codeletion status and volumetric analysis based on T2-weighted MRI.
The median preoperative and postoperative tumor volumes and EOR were 29.0 cm3 (range 1.3–222.7 cm3), 5.2 cm3 (range 0–156.1 cm3), and 85% (range 6%–100%), respectively. Median follow-up was 75.4 months, and there were 14 deaths (15%). Progression and malignant progression were identified in 31 (33%) and 20 (22%) cases, respectively. A greater EOR was associated with longer overall survival (p = 0.005) and progression-free survival (p = 0.004); however, a greater EOR did not prolong the interval to malignant progression, even when controlling for 1p/19q codeletion.
A greater EOR is associated with an improved survival profile for patients with WHO Grade II oligodendrogliomas. However, for this particular LGG patient population, the interval to tumor transformation is not influenced by cytoreduction. These data raise the possibility that the capacity for microsurgical resection to modulate malignant progression is mediated through biological mechanisms specific to nonoligodendroglioma LGG histologies.
Douglas A. Hardesty, Andrew B. Wolf, David G. Brachman, Heyoung L. McBride, Emad Youssef, Peter Nakaji, Randall W. Porter, Kris A. Smith, Robert F. Spetzler and Nader Sanai
Patients with atypical meningioma often undergo gross-total resection (GTR) at initial presentation, but the role of adjuvant radiation therapy remains unclear. The increasing prevalence of stereotactic radiosurgery (SRS) in the modern neurosurgical era has led to the use of routine postoperative radiation therapy in the absence of evidence-based guidelines. This study sought to define the long-term recurrence rate of atypical meningiomas and identify the value of SRS in affecting outcome.
The authors identified 228 patients with microsurgically treated atypical meningiomas who underwent a total of 257 resections at the Barrow Neurological Institute over the last 20 years. Atypical meningiomas were diagnosed according to current WHO criteria. Clinical and radiographic data were collected retrospectively.
Median clinical and radiographic follow-up was 52 months. Gross-total resection, defined as Simpson Grade I or II resection, was achieved in 149 patients (58%). The median proliferative index was 6.9% (range 0.4%–20.6%). Overall 51 patients (22%) demonstrated tumor recurrence at a median of 20.2 months postoperatively. Seventy-one patients (31%) underwent adjuvant radiation postoperatively, with 32 patients (14%) receiving adjuvant SRS and 39 patients (17%) receiving adjuvant intensity modulated radiation therapy (IMRT). The recurrence rate for patients receiving SRS was 25% (8/32) and for IMRT was 18% (7/39), which was not significantly different from the overall group. Gross-total resection was predictive of progression-free survival (PFS; relative risk 0.255, p < 0.0001), but postoperative SRS was not associated with improved PFS in all patients or in only those with subtotal resections.
Atypical meningiomas are increasingly irradiated, even after complete or near-complete microsurgical resection. This analysis of the largest patient series to date suggests that close observation remains reasonable in the setting of aggressive microsurgical resection. Although postoperative adjuvant SRS did not significantly affect tumor recurrence rates in this experience, a larger cohort study with longer follow-up may reveal a therapeutic benefit in the future.
Mark E. Oppenlander, Andrew B. Wolf, Laura A. Snyder, Robert Bina, Jeffrey R. Wilson, Stephen W. Coons, Lynn S. Ashby, David Brachman, Peter Nakaji, Randall W. Porter, Kris A. Smith, Robert F. Spetzler and Nader Sanai
Despite improvements in the medical and surgical management of patients with glioblastoma, tumor recurrence remains inevitable. For recurrent glioblastoma, however, the clinical value of a second resection remains uncertain. Specifically, what proportion of contrast-enhancing recurrent glioblastoma tissue must be removed to improve overall survival and what is the neurological cost of incremental resection beyond this threshold?
The authors identified 170 consecutive patients with recurrent supratentorial glioblastomas treated at the Barrow Neurological Institute from 2001 to 2011. All patients previously had a de novo glioblastoma and following their initial resection received standard temozolomide and fractionated radiotherapy.
The mean clinical follow-up was 22.6 months and no patient was lost to follow-up. At the time of recurrence, the median preoperative tumor volume was 26.1 cm3. Following re-resection, median postoperative tumor volume was 3.1 cm3, equating to an 87.4% extent of resection (EOR). The median overall survival was 19.0 months, with a median progression-free survival following re-resection of 5.2 months. Using Cox proportional hazards analysis, the variables of age, Karnofsky Performance Scale (KPS) score, and EOR were predictive of survival following repeat resection (p = 0.0001). Interestingly, a significant survival advantage was noted with as little as 80% EOR. Recursive partitioning analysis validated these findings and provided additional risk stratification at the highest levels of EOR. Overall, at 7 days after surgery, a deterioration in the NIH stroke scale score by 1 point or more was observed in 39.1% of patients with EOR ≥ 80% as compared with 16.7% for those with EOR < 80% (p = 0.0049). This disparity in neurological morbidity, however, did not endure beyond 30 days postoperatively (p = 0.1279).
For recurrent glioblastomas, an improvement in overall survival can be attained beyond an 80% EOR. This survival benefit must be balanced against the risk of neurological morbidity, which does increase with more aggressive cytoreduction, but only in the early postoperative period. Interestingly, this putative EOR threshold closely approximates that reported for newly diagnosed glioblastomas, suggesting that for a subset of patients, the survival benefit of microsurgical resection does not diminish despite biological progression.