TLR4 and head and neck squamous cell carcinoma: Compared with normal tissues, TLR4 gene is low expression in adrenocortical carcinoma (ACC), bladder urothelial carcinoma (BLCA), BRCA, cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC), cholangiocarcinoma (CHOL), head and neck squamous cell carcinoma (HNSC), kidney renal papillary cell carcinoma (KIRP), lung adenocarcinoma (LUAD), rectal adenocarcinoma (READ), thyroid cancer (THCA), UCEC, and uterine carcinoma (UCS).