Clinical trials for personalized glioblastoma radiotherapy: Markers for efficacy and late toxicity but often delayed treatment – Does that matter?

The extent of edema and tumor synchronous invasion into the subventricular zone and corpus callosum classify outcomes and radiotherapy strategies of glioblastomas

BACKGROUND AND PURPOSE

Irradiating glioblastoma preoperative edema (PE) remains controversial. We investigated the associations between tumors' PE extent with invasion into synchronous subventricular zone and corpus callosum (sSVZCC) and treatment outcomes to provide the clinical evidence for radiotherapy decision-making.

MATERIAL AND METHODS

Extensive PE (EPE) was defined as PE extending ≥2 cm from the tumor edge and extensive progressive disease (EPD) as tumors spreading ≥2 cm from the preoperative tumor edge along PE. The survival and progression patterns were analyzed according to EPE and sSVZCC invasion.

RESULTS

In total, 136 patients were followed for a median of 74.9 (range, 47.6-102.1) months. The median overall survival and progression-free survival were 19.7 versus 28.6 months (p = 0.005) and 11.0 versus 17.4 months (p = 0.011) in patients with EPE+ versus EPE-, and were 18.7 versus 25.4 months (p = 0.021) and 10.7 versus 14.6 months (p = 0.020) in those with sSVZCC+ versus sSVZCC-. The EPD rates for tumors with EPE-/sSVZCC-, EPE-/sSVZCC+, EPE+/sSVZCC-, and EPE+/sSVZCC+ were 2.8%, 7.1%, 37.0%, and 71.9%, respectively. In EPE+/sSVZCC+, tumor migration was associated with the PE extending along the corpus callosum (77.8%) and subventricular zone (50.0%).

CONCLUSIONS

Our results support the need for developing individualized irradiation strategies for glioblastomas according to EPE and sSVZCC.

Post-WBRT cognitive impairment and hippocampal neuronal depletion measured by in vivo metabolic MR spectroscopy: Results of prospective investigational study

BACKGROUND AND PURPOSE

The aim of this prospective study is to evaluate post-whole brain radiotherapy (WBRT) changes in hippocampal concentration of N-acetylaspartate (h-tNAA) as a marker of neuronal loss and to correlate those changes to neurocognitive function.

MATERIAL AND METHODS

Thirty-five patients with brain metastases underwent baseline single slice multi-voxel MR spectroscopy (MRS) examination for measurement of hippocampal h-tNAA together with baseline battery of neurocognitive tests focused on memory (Auditory Verbal Learning Test and Brief Visuospatial Memory Test - Revised) as well as quality of life questionnaires (EORTC QLQ-C30 a EORTC QLQ-BN20). Eighteen patients completed follow-up evaluation four months after standard WBRT (2 laterolateral fields, 10×3.0Gy, 6MV photons) and were included in this analysis. MRS and cognitive examinations were repeated and compared to baseline measurements.

RESULTS

Statistically significant decreases in h-tNAA were observed in the right (8.52-7.42mM; -12.9%, 95%CI: -7.6 to -16.4%) as well as in the left hippocampus (8.64-7.60mM; -12%, 95%CI: -7.9 to -16.2%). Statistically significant decline was observed in all AVLT and BVMT-R subtests with exception of AVLT_Recognition. Quality of life declined after WBRT (mean Δ -14.1±20.3 points in transformed 0-100 point scale; p=0.018) with no correlation to changes in hippocampal metabolite concentrations. Moderate positive correlation was observed between left h-tNAA concentration decrease and AVLT_TR decline (r=+0.32; p=0.24) as well as with AVLT_DR (r=+0.33; p=0.22) decline. Changes in right h-tNAA/Cr negatively correlated with AVLT_DR (r=-0.48; p=0.061). No correlation between right hippocampus h-tNAA and memory decline (AVLT) was observed.

CONCLUSIONS

Our results suggest hippocampal NAA concentrations decline after WBRT and MRS may be a useful biomarker for monitoring neuronal loss after radiotherapy.