Integrated circulating tumor DNA and T cell repertoire predict radiotherapeutic response and outcome in non-small cell lung cancer patients with brain metastasis

Dear editor,The scarcity of routinemetastatic biopsies or resection limits the finding of biomarkers of diagnosis and prognosis in patients with brain metastases.Derived from necrosis,apoptosis,and secretion of tumor cells,circulating tumor DNA(ctDNA)is widely distributed in various body fluids,including peripheral blood and cerebrospinal fluid(CSF),as an alternative biomarker for tumor-associated analysis[1].Fortunately,genomic alterations of blood ctDNA and CSF ctDNA have been proven as prognostic markers in non-small cell lung cancer(NSCLC)patients with brain metastasis[2,3].