About this Research Topic
High-grade glioma is the most common malignant brain tumor in adults. Treatment results remain dismal with an average survival of 14 to 15 months with standard of care therapy, consisting of maximal safe surgical resection, followed by radiotherapy with concomitant chemotherapy, followed by adjuvant chemotherapy. Advances have been made in understanding the molecular biology of glioblastoma as well as other cancers, resulting in a number of new treatment modalities, including tyrosine kinase inhibitors, angiogenesis inhibitors, gene therapy, immunotherapy and tumor treatment electric fields. The evaluation of response to these new modalities of treatment continues to be a challenge.
Radiologic assessment is the standard method of evaluating response to treatment of primary brain tumors and since the era of MRI imaging, there have been two major imaging criteria for assessing response, the MacDonald Criteria and RANO (Response Assessment in Neuro-Oncology). The former was based on contrast enhancement of lesions, while the latter and more recent incorporated changes in FLAIR imaging as well as corticosteroid use, and neurological evaluation. Even with these changes, the conundrum of distinguishing treatment response from tumor progression remains a challenge for physicians as well as clinical researchers. The distinction of pseudo-response versus true response in neuro-imaging following treatment with angiogenic agents continues to be a problem as well. The determination of inflammatory change, treatment damage, residual or progressive tumor and non-enhancing infiltrative tumor continues to challenge neuro-radiologists. As reported in Part I of this Research Topic, advances are being made in both MRI imaging as well as PET, with evaluation of new sequences, new tracers, as well as imaging analysis techniques and interpretation methods. Research imaging is continuing to be an important asset to Neuro-oncology as attempts are made to evaluate response to new therapeutic agents. In this Research Topic, more views, research results, and recommendations for optimal analyses of these provocative imaging variations will be presented with the goal of identifying the best technique or combination of techniques to determine true response versus pseudo-progression. Although this research question has not been adequately answered, much work is being done to assess how treatment response correlates with response rate and patient survival. These are very important issues to address as we explore new treatment modalities, and attempt to accurately assess their impact on tumor growth by imaging techniques. Novel imaging techniques will be required to keep pace with these new therapeutics and their unique effects on the brain as well as with our increasing understanding of the molecular biology of this difficult to treat cancer. This Research Topic provides updates on the research efforts in neuro-imaging and proposes a look to the future.
Keywords: Glioblastoma, pseudo-progression, pseudo-regression, angiogenesis, neuro-imaging
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