Patterns of management and outcomes of unifocal versus multifocal glioblastoma.

BACKGROUND: Glioblastoma (GBM) presents as a solitary lesion (unifocal), or as multiple discrete lesions (multifocal). Multifocal GBM may have a worse prognosis as compared to unifocal GBM, but existing data are limited to small institutional series. The purpose of the present study was to evaluate demographic and clinical characteristics of patients with unifocal versus multifocal GBM to highlight demographic differences and clinical outcomes for two groups of patients. METHODS: The National Cancer Database (NCDB) was queried (2004-2016) for patients newly diagnosed with either unifocal or multifocal GBM. Statistics included Kaplan-Meier overall survival (OS) analysis, along with Cox proportional hazards modeling. RESULTS: Of 45,268 total patients, 37,483 (82.8%) had unifocal GBM and 7,785 (17.2%) had multifocal GBM. Patients with unifocal GBM more frequently received gross total resection (GTR) (41.2% versus 25.8%, p < 0.001) and conventionally fractionated radiation therapy (RT) (48.2% versus 42.7%, p < 0.001). Patients with multifocal GBM had a higher rate of surgery with biopsy only (34.0% compared to 24.1%, p < 0.001). Median OS was 12.8 months versus 8.3 months (p < 0.001) for patients with unifocal GBM or multifocal GBM, respectively. On multivariate analysis, factors associated with improved OS included unifocal disease, MGMT methylation, RT use, and chemotherapy use. CONCLUSIONS: This is the largest study to date describing outcomes for patients with multifocal GBM, and it shows that multifocal GBM is associated with a decreased use both of GTR and conventionally fractionated RT, as well as worse median OS. Further research is needed to improve clinical outcomes for patients with multifocal GBM.

Combinatorial Anatomic and Functional Neural Tract Mapping for Stereotactic Radiosurgery Planning.

Introduction Stereotactic radiosurgery (SRS) is effective and safe for the treatment of the vast majority of brain metastases (BMs). SRS is increasingly used for the simultaneous treatment of multiple lesions, retreatment of recurrence, or subsequent treatment of new lesions. Although radiation injury is relatively uncommon, with the increased utilization of SRS, it is imperative to develop approaches to assess and mitigate radiation-induced neurologic toxicity. Multiple factors influence the development of radiation injury, including patient age, genomic variations, prior treatment, dose and volume treated, and anatomic location. Functional neural structure proximity to SRS targets is a critical factor in developing a systematic integrated risk assessment for SRS patients. Methods We developed an approach for risk assessment based on the combinatorial application of i) the anatomic localization of target lesions using a reference neuroanatomical/functional imaging atlas merged with patient-specific imaging and ii) validation with functional MRI (fMRI) and diffusion tensor imaging MRI (DTI-MRI) to identify neural tracts. Results In the case of a thalamic/midbrain junction breast carcinoma metastasis, the reference image analysis revealed proximity to the corticospinal tract (CST), which was validated by functional DTI-MRI. Dose-volume exposure of the CST could be estimated and considered in the development of a final treatment plan. Conclusion Merging pretreatment MR imaging with neuroanatomical/functional reference MRIs and subsequent validation with fMRI or DTI-MRI may prove to be a valuable approach to screen for neural risks in individual SRS patients. Incorporating this approach in larger studies could further our understanding of dose tolerances in a broad range of neural structures.