STAT3 and lung cancer: A large number of studies have shown that IL-6/JAK2/STAT3 signaling pathway is abnormally highly activated in a variety of cancers, such as gastric cancer (GC) (6, 7), breast cancer (BC) (8–10), liver cancer (11–13), colorectal cancer (CRC) (14, 15), colon cancer (16, 17), ovarian cancer (OC) (18, 19), lung cancer (20–22), pancreatic cancer (PC) (4, 5).