PurposeThis study aims to assess the prognostic value of inflammatory markers and clinical features in advanced or metastatic esophageal squamous cell carcinoma (ESCC) patients receiving anti-programmed death 1 (PD-1) treatment.MethodsBased on receiver operating characteristic curve (ROC) analysis, Youden’s indexes were applied to determine the cut-off values for inflammatory markers, including neutrophil-to-lymphocyte ratio (NLR), derived neutrophil-to-lymphocye ratio (dNLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), and systemic immune-inflammation index (SII). Wilcoxon test was conducted to evaluate the changes in above inflammatory markers. Kaplan-Meier method was utilized to estimate progression-free survival (PFS) and overall survival (OS), and the Log-rank test was used to compare the different survival between groups. Univariate and multivariate Cox regression analyses were performed to assess the prognostic value of inflammatory markers and clinical features.Results162 advanced or metastatic ESCC patients receiving anti-PD-1 treatment were enrolled in this retrospective study. The cut-off values of NLR, dNLR, MLR, PLR, and SII were 4.748, 2.214, 0.309, 250.505, and 887.895, respectively. NLR, dNLR, PLR, and SII declined significantly among the partial response (PR) (P<0.001, P<0.001, P=0.036, P<0.001), objective response rate (ORR) (P<0.001, P<0.001, P=0.036, P<0.001), and disease control rate (DCR) (P<0.001, P<0.001, P=0.038, P<0.001) groups, respectively. Significant increases were found in NLR (P<0.001), dNLR (P<0.001), MLR (P=0.001), and SII (P=0.024) when anti-PD-1 treatment failed. Multivariate Cox regression analysis indicated that NLR (P<0.001, P=0.002), lymph node metastasis (P=0.013, P=0.001), Eastern Cooperative Oncology Group Performance Status (ECOG PS) (P=0.008, P=0.002), and treatment lines (P=0.037, P=0.048) were significant prognostic indicators of PFS and OS. Additionally, SII (P=0.016) was also significantly related to OS in ESCC patients. The risk score model showed that low risk patients prolonged PFS and OS than those with middle or high risk (P<0.001, P<0.001).ConclusionInflammatory markers can reflect short-term outcomes of anti-PD-1 treatment for ESCC patients. NLR, lymph node metastases, ECOG PS, and treatment lines are significant prognostic indicators for PFS and OS. And the risk score model constructed based on the above factors has favourable prognostic predictive value.