This study was the first to report the prognostic value of PD-1, PD-L1, CTLA-4, TGF-β1, HIF-1α, IL-2 and IL-6 in peripheral blood on PFS and OS of SCLC.Few studies had reported the correlation between immune-related factors and SCLC survival in SCLC studies, while no studies had reported more than 7 immune-related factors at the same time.We investigated the changes of IL-2, IL-6, TGF-β1, HIF-1α, PD-1, PD-L1 and CTLA-4 in the course of chemotherapy compared with healthy controls, the relationships between each factor and clinical characteristics, the relationships among the 7 factors, and the relationships between the 7 factors and survival，prognosis.There were statistical differences in 7 cytokines between SCLC patients and healthy controls before and during treatment