Recent breakthroughs in circulating tumor DNA (ctDNA) technologies present a compelling opportunity to combine this emerging liquid biopsy approach with the field of radiogenomics, the study of how tumor genomics correlate with radiotherapy response and radiotoxicity. Canonically, ctDNA levels reflect metastatic tumor burden, although newer ultrasensitive technologies can be used after curative-intent radiotherapy of localized disease to assess ctDNA for minimal residual disease (MRD) detection or for post-treatment surveillance. Furthermore, several studies have demonstrated the potential utility of ctDNA analysis across various cancer types managed with radiotherapy or chemoradiotherapy, including sarcoma and cancers of the head and neck, lung, colon, rectum, bladder, and prostate . Additionally, because peripheral blood mononuclear cells are routinely collected alongside ctDNA to filter out mutations associated with clonal hematopoiesis, these cells are also available for single nucleotide polymorphism analysis and could potentially be used to detect patients at high risk for radiotoxicity. Lastly, future ctDNA assays will be utilized to better assess locoregional MRD in order to more precisely guide adjuvant radiotherapy after surgery in cases of localized disease, and guide ablative radiotherapy in cases of oligometastatic disease.

循环肿瘤 DNA (ctDNA) 技术的最新突破提供了一个绝佳的机会，可以将这种新兴的液体活检方法与放射基因组学领域结合起来，放射基因组学是研究肿瘤基因组学与放射治疗反应和放射毒性如何相关的研究。通常，ctDNA 水平反映了转移性肿瘤负荷，尽管在局部疾病的治疗性放射治疗后可以使用更新的超灵敏技术来评估 ctDNA，以进行微小残留病 (MRD) 检测或治疗后监测。此外，多项研究证明了 ctDNA 分析在采用放射疗法或放化疗治疗的各种癌症类型中的潜在效用，包括肉瘤和头颈癌、肺癌、结肠癌、直肠、膀胱和前列腺。此外，由于外周血单核细胞通常与 ctDNA 一起收集，以滤除与克隆造血相关的突变，因此这些细胞也可用于单核苷酸多态性分析，并有可能用于检测放射毒性高风险的患者。最后，未来的 ctDNA 检测将用于更好地评估局部 MRD，以便更精确地指导局部疾病术后的辅助放疗，并指导寡转移疾病的消融放疗。