STAT3 and cancer: STAT3 (signal transducer and activator of transcription 3) promotes multiple signaling pathways involving the mediation of cell proliferation, invasion, epithelial‐mesenchymal transition (EMT) and angiogenesis and has been considered as a key target for cancer therapy.17, 18, 19 Increasing evidence has shown the existence of genetic variation and amplification of STAT3 in major malignancies.19, 20, 21, 22 STAT3 signaling pathway plays a vital role in cancer progression and tumor microenvironment,23, 24 indicating that it may be used as a therapeutic target.