## 6 Conclusions  
Identification and validation of biomarkers closely related to radiosensitivity/radiotoxicity is a critical step in oncology for identifying those patients with potential intolerability to RT. Cellular radiosensitivity is influenced by various treatment-specific, as well as patient-specific factors. The \(\gamma\)H2 AX protein emerged as one prominent marker for radiosensitivity prediction. A practical and efficient method for assessing an individual's global DSB repair capacity has been measuring \(\gamma\)H2 AX via flow cytometry, which holds promise to enable the prediction of an individual's radiosensitivity and the risk of adverse effects to RT [196]. Moreover, ELISA-based assays against H2 AX and TP53 have been proposed for monitoring the efficacy of radiotherapy in cancer patients [197]. The findings of the study of [PERSON] et al., 2022, showed a decrease in H2 AX levels after radiotherapy, making it a useful indicator of DNA damage response and radiation sensitivity, and activation of TP53 via radiotherapy, as its expression increases in cancer patients, indicating its role as a marker for DNA damage response in early radiation exposure. Furthermore, interleukin-6 (IL-6) and interleukin-1 beta (IL-19) are promising biomarkers for common clinical practice, especially in the format of ELISA assays, as they are easily operated and cost-efficient. Finally, the still ongoing research in cell-free DNA (cfDNA) shows that it is a propitious liquid biomarker for non-invasive diagnosis, treatment selection, tumor response to radiation therapy, predicting treatment outcomes and evaluating radiotoxicity. Modern oncology is entering an era of individualized onco-treatment and risk assessment. Therefore, the discovery of biomarkers in accessible biological samples such as blood (serum, plasma, blood cells, etc.) is of particular importance. The accurate identification of such protein molecules as novel predictive biomarkers, associated with normal tissue radiosensitivity and toxicity, will open new avenues for the optimization of personalized RT therapies against cancer. The incorporation of radiosensitivity biomarkers and in general radiobiology approaches into clinical routine represents an upcoming pivotal advancement in the field of radiation oncology and personalized medicine. The aforementioned biomarkers have demonstrated, in many cases, their ability to predict patients' radiosensitivity and individual patient responses to radiation therapy, thereby providing clinicians with the tools to tailor treatment regimens with unprecedented precision. All of the above explain the rationale for this work, i.e., toward a concise and critical review of such molecular markers. By harnessing the power of these biomarkers, healthcare professionals can minimize the risks of overexposure or undertreatment, optimizing therapeutic outcomes while minimizing unnecessary side effects. Moreover, the integration of these biomarkers into routine clinical practice holds the promise of opening new avenues for innovative therapeutic strategies, ultimately enhancing the quality of care for cancer patients. As we continue to refine our understanding of radiosensitivity biomarkers for clinical applications, their importance in the field cannot be overstated, offering only a beacon of hope for more effective and individualized cancer treatments. Conceptualization, A.G.G. ; methodology, A.G., S.A.K. and A.G.G. ; investigation, A.G., S.A.K., E.C.L. and G.M. ; resources, A.G.G. ; data curation, A.G., S.A.K., S.T., S.L. and V.S. ; writing--original draft preparation, S.A.K., A.G., G.M., E.C.L. and S.T. ; writing--review and editing, A.G., S.L., S.A.K., G.I.T., K.T., S.T., C.K. and A.G.G.G. ; supervision, A.G.G. and G.I.T. ; project administration, A.G.G., funding acquisition, A.G.G. All authors have read and agreed to the published version of the manuscript.