For TCGA tumors and adjacent normal tissues, CLDN6 expression was significantly upregulated in eight cancer types, including breast invasive carcinoma (BRCA), cholangiocarcinoma (CHOL), colon adenocarcinoma (COAD), esophageal carcinoma (ESCA), head and neck squamous cell carcinoma (HNSC), lung adenocarcinoma (LUAD), STAD, and UCEC, while it was downregulated in kidney chromophobe (KICH) and kidney renal clear cell carcinoma (KIRC) (Figure 1C). Here, CLDN6 is linked to head and neck squamous cell carcinoma.