Aim: To explore the clinical utility of the systemic immune-inflammation index (SII) for predicting the prognosis of esophageal squamous cell carcinoma (ESCC). Patients & methods: After calculating the SII in 180 patients with ESCC, the relationship between SII values and the pre-/post-radiotherapy SII ratio and overall survival was determined. Results: The median overall survival was 649 days for the entire group and 909 and 466 days for the high and low pre-/post-radiotherapy SII ratio groups, respectively. Multivariate analysis identified Karnofsky performance status (p = 0.045), lymphatic metastasis (p = 0.032), mid-radiotherapy SII (p < 0.001) and pre-/post-radiotherapy SII ratio (p = 0.003) as independent prognostic factors. Conclusion: The pre-/post-radiotherapy SII ratio and mid-radiotherapy SII are potentially effective markers for predicting ESCC prognosis.

The role of TLR4 (toll like receptor 4), a key molecule of the classical innate immune pathway, in individual tumors requires further exploration. In this study, numerous databases and tools, such as TCGA, GTEx, cBioportal, GSCALite, and GDSC, were utilized to systematically analyze the prognostic and immunological potential of TLR4 in tumors. The expression levels and mutational dynamics of TLR4 in pan-cancer were investigated. The prognostic potential of TLR4 was analyzed using Kaplan-Meier (KM) analysis. Results showed the levels of TLR4 in tumor tissues were significantly lower as compared to those in normal tissues in most cancers and were strongly correlated with the patient’s outcomes. The mutant genes associated with TLR4 were mainly enriched in the PI3K-AKT pathway. This could be a potential pathway for radiotherapy to activate the tumor immune microenvironment via TLR4/MAP. In tumors, the TLR4 mutations were closely associated with the M1/M2 polarization of macrophages. TLR4 and its ligand CD14 were significantly negatively associated with immunosuppressed MDSCs and TAM M2. The intervention of TLR4-dependent signaling pathways might be a promising strategy to reduce tolerance to ICB treatment in the post-immune era. In conclusion, this study expands the potential of TLR4 as an immune target in tumor therapy.