Location of brain tumor intersecting white matter tracts predicts patient prognosis.

Brain tumor cells invade adjacent normal brain along white matter (WM) bundles of axons. We therefore hypothesized that the location of tumor intersecting WM tracts would be associated with differing survival. This study introduces a method, voxel-wise survival analysis (VSA), to determine the relationship between the location of brain tumor intersecting WM tracts and patient prognosis. 113 primary glioblastoma (GBM) patients were retrospectively analyzed for this study. Patient specific tumor location, defined by contrast-enhancement, was combined with diffusion tensor imaging derived tractography to determine the location of axons intersecting tumor enhancement (AXITEs). VSA was then used to determine the relationship between the AXITE location and patient survival. Tumors intersecting the right anterior thalamic radiation (ATR), right inferior fronto-occipital fasciculus (IFOF), right and left cortico-spinal tract (CST), and corpus callosum (CC) were associated with decreased overall survival. Tumors intersecting the CST, body of the CC, right ATR, posterior IFOF, and inferior longitudinal fasciculus are associated with decreased progression-free survival (PFS), while tumors intersecting the right genu of the CC and anterior IFOF are associated with increased PFS. Patients with tumors intersecting the ATR, IFOF, CST, or CC had significantly improved survival prognosis if they were additionally treated with bevacizumab. This study demonstrates the usefulness of VSA by locating AXITEs associated with poor prognosis in GBM patients. This information should be included in patient-physician conversations, therapeutic strategy, and clinical trial design.

Comparison of Radiation Treatment Volumes for Borderline Resectable Pancreatic Cancer in Contemporary Clinical Trials.

OBJECTIVES: Optimal radiation target volumes for neoadjuvant therapy in patients with borderline resectable pancreatic cancer (BRPCa) are undefined. Most local recurrences are near the celiac axis and superior mesenteric artery. Methods for generating radiation target volumes include symmetric expansion around the tumor or a customized vascular based approach. We investigated 3 current prospective trials' coverage of vascular regions at increased risk of recurrence by comparing them to 2 reference standards. MATERIALS AND METHODS: Fourteen computed tomography simulation scans from an institutional prospective trial on BRPCa were used to replicate distinct volumes corresponding to each of 3 contemporary BRPCa trials. Trial volumes were compared with 2 reference volumes (vascular planning target volume and Hopkins planning target volume), which were both based on vascular regions at increased risk of recurrence. Boolean operators and DICE analyses were performed to evaluate trial volume coverage of reference standards. RESULTS: A total of 42 target volumes and 28 reference volumes were created using the 14-patient data set. DICE coefficients were highly variable ranging from 0.11 to 0.99. Mean % coverage of reference volumes ranged from 5.8% to 98.6%. CONCLUSIONS: The wide range of DICE coefficients and coverage indicate heterogeneity in high risk vascular target coverage using symmetric Boolean expansions from the primary tumor. This approach may inadequately cover regions at high risk of local recurrence in BRPCa. A customized clinical target volume that specifically includes the superior mesenteric artery and celiac axis will improve coverage to this region and will account for individual and tumor variability.