STAT3 and non-small cell lung carcinoma: In NSCLC, persistent STAT3 activation is present in 22–65% of cases, and the activation of STAT3 is involved in tumor proliferation, chemotherapy tolerance, and poor clinical outcome [21–24]., STAT3 activation is observed in every case of SCLC [25], suggesting that STAT3 activation plays a very important role in SCLC progression.