According to each point in time of ctDNA, to analyze the dynamic changes of tumor burden and clonal subtypes which to evaluate the application value of ctDNA in curative efficacy evaluation.~Compare the two time points before and after radiotherapy and chemotherapy treatment of the cell free DNA (cfDNA) concentration and tumor burden, analysis the correlation between the changes and prognosis.
The purpose of this study is to evaluate the application value of circulating tumor DNA(ctDNA) with efficacy evaluation and prognostic assessment in patients with unresectable SCLC, who were receiving radiotherapy and chemotherapy treatment.