TLR4 and esophageal squamous cell carcinoma: Specifically, expression of TLR3, TLR4, TLR5, and TLR9 has been suggested as a potential mediator of the progression from reflux disorders to esophageal adenocarcinoma [29] Meanwhile, the increased expression levels of TLR3, TLR4, and TLR9 have been observed in esophageal squamous cell carcinoma (SCC) associated with lymphatic metastasis, with increased expression of TLR7 and TLR9 associating with advanced disease [30].