TLR4 and central nervous system cancer: Clinical data indicate that elevated expression of TLR4 is associated with poor prognosis in patients with liver and colorectal cancer.331,332 Similarly, high expression levels of TLR9 have been linked to unfavorable outcomes in patients with liver cancer, glioma, HCC, and esophageal adenocarcinoma.331,333,334 Preclinical studies indicate that activation of TLRs can generate pro-tumorigenic inflammatory signals and survival cues for tumor cells.