Alireza M. Mohammadi, Jason L. Schroeder, Lilyana Angelov, Samuel T. Chao, Erin S. Murphy, Jennifer S. Yu, Gennady Neyman, Xuefei Jia, John H. Suh, Gene H. Barnett and Michael A. Vogelbaum
The impact of the stereotactic radiosurgery (SRS) prescription dose (PD) on local progression and radiation necrosis for small (≤ 2 cm) brain metastases was evaluated.
An institutional review board–approved retrospective review was performed on 896 patients with brain metastases ≤ 2 cm (3034 tumors) who were treated with 1229 SRS procedures between 2000 and 2012. Local progression and/or radiation necrosis were the primary end points. Each tumor was followed from the date of radiosurgery until one of the end points was reached or the last MRI follow-up. Various criteria were used to differentiate tumor progression and radiation necrosis, including the evaluation of serial MRIs, cerebral blood volume on perfusion MR, FDG-PET scans, and, in some cases, surgical pathology. The median radiographic follow-up per lesion was 6.2 months.
The median patient age was 56 years, and 56% of the patients were female. The most common primary pathology was non–small cell lung cancer (44%), followed by breast cancer (19%), renal cell carcinoma (14%), melanoma (11%), and small cell lung cancer (5%). The median tumor volume and median largest diameter were 0.16 cm3 and 0.8 cm, respectively. In total, 1018 lesions (34%) were larger than 1 cm in maximum diameter. The PD for 2410 tumors (80%) was 24 Gy, for 408 tumors (13%) it was 19 to 23 Gy, and for 216 tumors (7%) it was 15 to 18 Gy. In total, 87 patients (10%) had local progression of 104 tumors (3%), and 148 patients (17%) had at least radiographic evidence of radiation necrosis involving 199 tumors (7%; 4% were symptomatic). Univariate and multivariate analyses were performed for local progression and radiation necrosis. For local progression, tumors less than 1 cm (subhazard ratio [SHR] 2.32; p < 0.001), PD of 24 Gy (SHR 1.84; p = 0.01), and additional whole-brain radiation therapy (SHR 2.53; p = 0.001) were independently associated with better outcome. For the development of radiographic radiation necrosis, independent prognostic factors included size greater than 1 cm (SHR 2.13; p < 0.001), location in the corpus callosum (SHR 5.72; p < 0.001), and uncommon pathologies (SHR 1.65; p = 0.05). Size (SHR 4.78; p < 0.001) and location (SHR 7.62; p < 0.001)—but not uncommon pathologies—were independent prognostic factors for the subgroup with symptomatic radiation necrosis.
A PD of 24 Gy results in significantly better local control of metastases measuring < 2 cm than lower doses. In addition, tumor size is an independent prognostic factor for both local progression and radiation necrosis. Some tumor pathologies and locations may also contribute to an increased risk of radiation necrosis.
Benjamin B. Whiting, Bryan S. Lee, Vaidehi Mahadev, Hamid Borghei-Razavi, Sanchit Ahuja, Xuefei Jia, Alireza M. Mohammadi, Gene H. Barnett, Lilyana Angelov, Shobana Rajan, Rafi Avitsian and Michael A. Vogelbaum
Current management of gliomas involves a multidisciplinary approach, including a combination of maximal safe resection, radiotherapy, and chemotherapy. The use of intraoperative MRI (iMRI) helps to maximize extent of resection (EOR), and use of awake functional mapping supports preservation of eloquent areas of the brain. This study reports on the combined use of these surgical adjuncts.
The authors performed a retrospective review of patients with gliomas who underwent minimal access craniotomy in their iMRI suite (IMRIS) with awake functional mapping between 2010 and 2017. Patient demographics, tumor characteristics, intraoperative and postoperative adverse events, and treatment details were obtained. Volumetric analysis of preoperative tumor volume as well as intraoperative and postoperative residual volumes was performed.
A total of 61 patients requiring 62 tumor resections met the inclusion criteria. Of the tumors resected, 45.9% were WHO grade I or II and 54.1% were WHO grade III or IV. Intraoperative neurophysiological monitoring modalities included speech alone in 23 cases (37.1%), motor alone in 24 (38.7%), and both speech and motor in 15 (24.2%). Intraoperative MRI demonstrated residual tumor in 48 cases (77.4%), 41 (85.4%) of whom underwent further resection. Median EOR on iMRI and postoperative MRI was 86.0% and 98.5%, respectively, with a mean difference of 10% and a median difference of 10.5% (p < 0.001). Seventeen of 62 cases achieved an increased EOR > 15% related to use of iMRI. Seventeen (60.7%) of 28 low-grade gliomas and 10 (30.3%) of 33 high-grade gliomas achieved complete resection. Significant intraoperative events included at least temporary new or worsened speech alteration in 7 of 38 cases who underwent speech mapping (18.4%), new or worsened weakness in 7 of 39 cases who underwent motor mapping (18.0%), numbness in 2 cases (3.2%), agitation in 2 (3.2%), and seizures in 2 (3.2%). Among the patients with new intraoperative deficits, 2 had residual speech difficulty, and 2 had weakness postoperatively, which improved to baseline strength by 6 months.
In this retrospective case series, the combined use of iMRI and awake functional mapping was demonstrated to be safe and feasible. This combined approach allows one to achieve the dual goals of maximal tumor removal and minimal functional consequences in patients undergoing glioma resection.