We found ICOS is significantly overexpressed in the multiple cancers when compared with normal tissues, including BRCA (breast invasive carcinoma), ESCA (esophageal carcinoma), HNSC (head and neck cancer), KIRC (kidney renal clear cell carcinoma), KIRP (kidney renal papillary cell carcinoma), LIHC (liver hepatocellular carcinoma), STAD (stomach adenocarcinoma), UCEC (uterine corpus endometrial carcinoma), however, ICOS is upregulated in LUAD (lung adenocarcinoma), LUSC (lung squamous cell carcinoma), as well as THCA (thyroid carcinoma). This evidence concerns the gene ICOS and lung adenocarcinoma.