# Terahertz Time-Domain Spectroscopy of Glioma Patient Blood Plasma: Diagnosis and Treatment
## 5 Conclusions  
In this work, we studied the blood plasma of patients with glioma using THz-TDS and ML. We carried out a comparative analysis of the THz spectral data of this group with a group of patients with SCD and healthy donors. The XGBoost and RF predictive data models showed the best differentiation of the glioma patients' group from the other groups (AUC = 0.81-0.84). It was shown that THz spectroscopy combined with ML makes it possible to separate with high accuracy the blood plasma of glioma patients before and after tumor removal surgery. The most informative THz frequencies were determined. They coincided, for these, in the experimental mouse model of human glioblastoma found by us earlier [41]. This confirms the potential of THz spectroscopy and ML in the control of glioma treatment. The main limitation of this study is the number of processed samples. We believe that more robust ML models can be constructed by increasing the dataset volume. **Supplementary Materials:** The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app13095434/s1](https://www.mdpi.com/article/10.3390/app13095434/s1)]([https://www.mdpi.com/article/10.3390/app13095434/s1](https://www.mdpi.com/article/10.3390/app13095434/s1)), Figure S1: Graph of the cumulative explained variance to find the maximum allowed number of PCs for (a) blood plasma of glioma patients and healthy donors (Case 1); (b) blood plasma of glioma patients and patients with skull craniectomy defects (Case 2); Figure S2: PCA score plot with data standardization (a) and without (b) for glioma patients and healthy donors, for PC1 and PC2; Figure S3: PCA score plot with data standardization (a) and without (b) for glioma patients and healthy donors, for PC1 and PC9; Figure S4: PCA score plot with data standardization (a) and without (b) for glioma patients and patients without glioma (with skull craniectomy defects), for PC1 and PC5; Figure S5: ROC AUC analysis: (a)--linear kernel SVM Case 1; (b) linear kernel SVM Case 2; (c)--RF Case 1; (d)--RF Case 2; (e)--XGBoost Case 1; (f)--XGBoost Case 2; Figure S6: A graph of cumulative explained variance for determining the acceptable number of principal components; Figure S7: Graph of ROC-AUC analysis of different ML methods for separation of blood plasma of glioma patients before and after surgery: (a)--linear kernel SVM; (b)--RF; (c)--XGBoost. **Author Contributions:** Conceptualization, O.C., Y.P., Y.K. and A.S.; methodology, Y.K., Y.P., D.V., M.K., N.N. and A.K. ; software, D.V. and A.P. ; validation, D.V., A.K., A.P., M.K., N.N., E.S., V.G. and V.S. ; formal analysis, D.V., A.K., E.S., M.K., V.G., V.S. and N.N. ; investigation, A.K., E.S., V.G., A.P. and N.N. ; writing--original draft preparation, O.C., Y.P., D.V., A.K., E.S. and V.S. ; writing--review and editing, O.C., Y.P., Y.K., D.V., A.K., A.P., E.S., V.G., V.S., N.N., M.K. and A.S.; visualization, D.V., A.K. and A.P. ; supervision, A.S.; project administration, O.C. and Y.K. ; funding acquisition, N.N., Y.K. and A.S. All authors have read and agreed to the published version of the manuscript. **Funding:** This research was funded by the Ministry of Science and Higher Education of the Russian Federation: project No. 121032400052-6. This work was performed partly within the State Assignment of FSRC \"Crystallography and Photonics\" RAS. This work has been supported by the Interdisciplinary Scientific and Educational School of Moscow University <<Photonic and Quantum Technologies. Digital Medicine>> for part of the results analysis. The research was carried out with the support of a grant under the Decree of the Government of the Russian Federation No. 220 of 9 April 2010 (Agreement No. 075-15-2021-615 of 4 June 2021). The work of [PERSON], A.K. and Y.K. was supported by the Ministry of Science and Higher Education of the Russian Federation (budget funds for the V.E. Zuev Institute of Atmospheric Optics of the Siberian Branch of the Russian Academy of Sciences).