MUC1 and cancer: In this study, accordingly, the combination of three peptide antigens derived from CD25, MUC1, and VEGFR1 was used to develop an enzyme‐linked immunosorbent assay (ELISA) in‐house to obtain additive signals for detection of natural IgG antibodies against these 3 target molecules in NSCLC; we also used the in‐house ELISA to detect natural IgG antibodies for cancer‐related molecules POU5F1 and TNF‐α in this malignancy.