There have been several reports on the prognostic significance of plasma IL-6 in ICI-treated patients with various cancers, including NSCLC (Kang et al., 2020; Keegan et al., 2020; Laino et al., 2020; Kauffmann-Guerrero et al., 2021; Liu et al., 2022; Wang et al., 2022; Hu et al., 2023; Inoue et al., 2023); however, the clinical significance of its receptors, sIL-6R or sgp130, in the plasma has not been clarified. This evidence concerns the gene IL6 and cancer.