Characterization of the serum metabolome following radiation treatment in patients with high-grade gliomas.
Level 4 - case-series / case-control
Prospective single-arm case series evaluating biomarker changes over time without a control group
PubMed 27039175 · doi:10.1186/s13014-016-0626-6
What was done
Fasting serum samples were collected from 11 glioblastoma patients at hospital admittance, before the first radiotherapy treatment, and on the mornings following the second and fifth radiation doses. Samples were analyzed using gas-chromatographic time-of-flight mass spectrometry (GC-TOF-MS) with chemometrics-based bioinformatics. Findings were compared to previously acquired microdialysis data from the tumor extracellular fluid of the same patients.
What was found
A significant change in serum metabolite patterns occurred during early radiotherapy compared to pre-treatment levels. In total, 68 metabolites decreased in concentration (including all detected and identified amino acids, fatty acids, myo-inositol, creatinine, and urea), while 16 metabolites increased (including citric acid). While overall serum and tumor tissue patterns showed common individual-level shifts—such as matching changes in ornithine, tyrosine, and urea—glutamine and glutamate were reduced in serum but elevated in tumor extracellular fluid.
Why it matters
Because MRI cannot reliably assess glioblastoma treatment effects until months after radiotherapy initiation, early blood-based metabolomic shifts could serve as a non-invasive tool to monitor early radiation response.
Limits
The study is limited by a very small sample size (n = 11) and lacks an untreated or healthy control group. The abstract reports no clinical outcome or survival correlations, and some metabolite shifts in serum diverged directly from those observed in tumor tissue.
Cited by
- partial Brain radiation increases extracellular glucose and glutamine levels, elevating blood sugar and upregulating cortisol in patients.