In lung cancer-bearing mice, Gal-9 promoted survival by inducing the differentiation of macrophages.25 The apoptosis of tumor cells induced by Gal-9 was observed in liver cancer and esophageal carcinoma.26–28 In our study, we aimed to reveal the expression patterns of Gal-9 on tumor cells and tumor-infiltrating lymphocytes (TILs) by immunohistochemistry (IHC) tests, as well as its connection with other immune markers in SCLC. The gene discussed is LGALS9; the disease is lung cancer.