Krishna C. Joshi, Alankrita Raghavan, Baha’eddin Muhsen, Jason Hsieh, Hamid Borghei-Razavi, Samuel T. Chao, Gene H. Barnett, John H. Suh, Gennady Neyman, Varun R. Kshettry, Pablo F. Recinos, Alireza M. Mohammadi and Lilyana Angelov
Gamma Knife radiosurgery (GKRS) has been successfully used for the treatment of intracranial meningiomas given its steep dose gradients and high-dose conformality. However, treatment of skull base meningiomas (SBMs) may pose significant risk to adjacent radiation-sensitive structures such as the cranial nerves. Fractionated GKRS (fGKRS) may decrease this risk, but until recently it has not been practical with traditional pin-based systems. This study reports the authors’ experience in treating SBMs with fGKRS, using a relocatable, noninvasive immobilization system.
The authors performed a retrospective review of all patients who underwent fGKRS for SBMs between 2013 and 2018 delivered using the Extend relocatable frame system or the Icon system. Patient demographics, pre- and post-GKRS tumor characteristics, perilesional edema, prior treatment details, and clinical symptoms were evaluated. Volumetric analysis of pre-GKRS, post-GKRS, and subsequent follow-up visits was performed.
Twenty-five patients met inclusion criteria. Nineteen patients were treated with the Icon system, and 6 patients were treated with the Extend system. The mean pre-fGKRS tumor volume was 7.62 cm3 (range 4.57–13.07 cm3). The median margin dose was 25 Gy delivered in 4 (8%) or 5 (92%) fractions. The median follow-up time was 12.4 months (range 4.7–17.4 months). Two patients (9%) experienced new-onset cranial neuropathy at the first follow-up. The mean postoperative tumor volume reduction was 15.9% with 6 patients (27%) experiencing improvement of cranial neuropathy at the first follow-up. Median first follow-up scans were obtained at 3.4 months (range 2.8–4.3 months). Three patients (12%) developed asymptomatic, mild perilesional edema by the first follow-up, which remained stable subsequently.
fGKRS with relocatable, noninvasive immobilization systems is well tolerated in patients with SBMs and demonstrated satisfactory tumor control as well as limited radiation toxicity. Future prospective studies with long-term follow-up and comparison to single-session GKRS or fractionated stereotactic radiotherapy are necessary to validate these findings and determine the efficacy of this approach in the management of SBMs.
Matthew M. Grabowski, Pablo F. Recinos, Amy S. Nowacki, Jason L. Schroeder, Lilyana Angelov, Gene H. Barnett and Michael A. Vogelbaum
The impact of extent of resection (EOR) on survival for patients with glioblastoma (GBM) continues to be a point of debate despite multiple studies demonstrating that increasing EOR likely extends survival for these patients. In addition, contrast-enhancing residual tumor volume (CE-RTV) alone has rarely been analyzed quantitatively to determine if it is a predictor of outcome. The purpose of this study was to evaluate the effect of CE-RTV and T2/FLAIR residual volume (T2/F-RV) on overall survival.
A retrospective review of 128 patients who underwent primary resection of supratentorial GBM followed by standard radiation/chemotherapy was undertaken utilizing quantitative, volumetric analysis of pre- and postoperative MR images. The results were compared with clinical data obtained from the patients' medical records.
At analysis, 8% of patients were alive, and no patients were lost to follow-up. The overall median survival was 13.8 months, with a median Karnofsky Performance Scale (KPS) score of 90 at presentation. The median contrast-enhancing preoperative tumor volume (CE-PTV) was 29.0 cm3, and CE-RTV was 1.2 cm3, equating to a 95.8% median EOR. The median T2/F-RV was 36.8 cm3. CE-PTV, CE-RTV, T2/F-RV, and EOR were all statistically significant predictors of survival when controlling for age and KPS score. A statistically significant benefit in survival was seen with a CE-RTV less than 2 cm3 or an EOR greater than 98%. Evaluation of the volumetric analysis methodology was performed by observers of varying degrees of experience—an attending neurosurgeon, a fellow, and a medical student. Both the medical student and fellow recorded correlation coefficients of 0.98 when compared with the attending surgeon's measured volumes of CE-PTV, while for CE-RTV, correlation coefficients of 0.67 and 0.71 (medical student and fellow, respectively) were obtained.
CE-RTV and EOR were found to be significant predictors of survival after GBM resection. CERTV was the more significant predictor of survival compared with EOR, suggesting that the volume of residual contrast-enhancing tumor may be a more accurate and meaningful reflection of the pathobiology of GBM.
Alireza Mohammad Mohammadi, Pablo F. Recinos, Gene H. Barnett, Robert J. Weil, Michael A. Vogelbaum, Samuel T. Chao, John H. Suh, Nicholas F. Marko, Paul Elson, Gennady Neyman and Lilyana Angelov
The authors evaluated overall survival and factors predicting outcome in patients with ≥ 5 brain metastases who were treated with Gamma Knife surgery (GKS).
Medical records from patients with ≥ 5 brain metastases treated with GKS between 1997 and 2010 at the Cleveland Clinic Gamma Knife Center were retrospectively reviewed. Patient demographics, tumor characteristics, treatment-related factors, and outcome data were evaluated.
One hundred seventy patients were identified, with a median age of 58 years. The female/male ratio was 1.2:1. Gamma Knife surgery was used as an upfront treatment in 35% of patients and as salvage treatment in 65% of patients with multiple brain metastases. The median overall survival after GKS was 6.7 months (95% CI 5.5–8.1). At the time of GKS, 128 patients (75%) had concurrent extracranial metastases, and in 69 patients (41%) multiple extracranial sites were involved. Ninety-two patients (54%) had a history of whole-brain radiation therapy, and 158 patients (93%) had a Karnofsky Performance Scale (KPS) score ≥ 70. The median total intracranial disease volume was 3.2 cm3 (range 0.2–37.2 cm3). A total intracranial tumor volume ≥ 10 cm3 was observed in 32 patients (19%). Lower KPS score at the time of treatment (p < 0.0001), patient age > 60 years (p = 0.004), multiple extracranial metastases (p = 0.0001), and greater intracranial burden of disease (p = 0.03) were prognostic factors for poor outcome in the univariate and multivariate analyses.
In this study, GKS was safe and effective for upfront and salvage treatment in patients with ≥ 5 brain metastases. Gamma Knife surgery should be considered as an additional treatment modality for these patients, especially in the subset of patients with favorable prognostic factors.