Radiotherapy up to 10 Gy given in five fractions does not influence the glucose metabolism nor does it induce any acute cytotoxic effect detected with glutamate or glycerol in malignant glioma, as assessed by microdialysis. The study confirms the glycolytic properties of glucose metabolism in malignant glioma.

BACKGROUND: High-grade gliomas are associated with poor prognosis. Tumour heterogeneity and invasiveness create challenges for effective treatment and use of systemically administrated drugs. Furthermore, lack of functional predictive response-assays based on drug efficacy complicates evaluation of early treatment responses. METHODS: We used microdialysis to deliver cisplatin into the tumour and to monitor levels of metabolic compounds present in the tumour and non-malignant brain tissue adjacent to tumour, before and during treatment. In parallel, we collected serum samples and used multivariate statistics to analyse the metabolic effects. RESULTS: We found distinct metabolic patterns in the extracellular fluids from tumour compared to non-malignant brain tissue, including high concentrations of a wide range of amino acids, amino acid derivatives and reduced levels of monosaccharides and purine nucleosides. We found that locoregional cisplatin delivery had a strong metabolic effect at the tumour site, resulting in substantial release of glutamic acid, phosphate, and spermidine and a reduction of cysteine levels. In addition, patients with longtime survival displayed different treatment response patterns in both tumour and serum. Longer survival was associated with low tumour levels of lactic acid, glyceric acid, ketoses, creatinine and cysteine. Patients with longer survival displayed lower serum levels of ketohexoses, fatty acid methyl esters, glycerol-3-phosphate and alpha-tocopherol, while elevated phosphate levels were seen in both tumour and serum during treatment. CONCLUSION: We highlight distinct metabolic patterns associated with high-grade tumour metabolism, and responses to cytotoxic cisplatin treatment.

The knowledge of response to radiation in the immuno-microenvironment of high grade gliomas is sparse. In vitro results have indicated an inflammatory response of myeloid cells after irradiation. Therefore, microdialysis was used to verify whether this is operative in tumor tissue and brain adjacent to tumor (BAT) after clinical radiotherapy of patients with high grade glioma. Stereotactic biopsies and implantation of microdialysis catheters in tumor tissue and BAT were performed in eleven patients with high-grade glioma. The patients were given daily radiation fractions of 2–3.4 Gy. Microdialysis samples were collected before radiotherapy and during the first five days of radiation. Cytokines, glucose metabolites, glutamate and glycerol were analyzed. Immunohistochemistry was performed to detect macrophages (CD68) and monocytes (CD163) as well as IL-6, IL-8 and MCP-1. A significant increase of IL-8, MCP-1 and MIP-1a were detected in tumor tissue already after the first dose of radiation and increased further during 5 days of radiation. IL-6 did also increase but after five fractions of radiation. In BAT, the cytokine response was modest with significant increase of IL-8 after third dose of radiation. We found a positive correlation between baseline IL-8 and IL-6 microdialysis levels in tumor tissue and survival. Glucose metabolites or glycerol and glutamate did not change during radiation. In all tumors staining for macrophages was demonstrated. IL-6 was found in viable tumor cells while MCP-1 was demonstrated in macrophages or tumor matrix. Our findings suggest that radiation induces a rapid enhancement of the prevailing inflammation in high-grade glioma tissue. The microdialysis technique is feasible for this type of study and could be used to monitor metabolic changes after different interventions.Electronic supplementary materialThe online version of this article (doi:10.1007/s11060-016-2271-1) contains supplementary material, which is available to authorized users.

Using the RUAM, an international multidisciplinary panel established criteria for appropriate treatment choice in patients with PPSS. These may be helpful to educate physicians and to improve consistency and quality of care. These slides can be retrieved under Electronic Supplementary Material.

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