Positive lymph node ratio is an important index to predict long-term survival for advanced esophageal squamous carcinoma patients (II∼III) with R0 resection--a SEER-based analysis

Background: Esophageal squamous carcinoma (ESCC) is one of the most malignant cancers in the world due to nodal metastasis. Therefore, a reasonable nodal staging system is extremely important for further treatment strategies. Recently the positive lymph node ratio (PLNR) is an important prognostic factor in various solid tumors Method: In this study, we investigated the clinical significance of the PLNR in stage II∼III ESCC patients. We collected the pathological characteristics of 272 stage II∼III ESCC patients from the SEER database from 2004–2016. ROC curves were used to calculate the best cutoff value of the PLNR; Pearson's Chi-square (χ2) and Fisher's exact probability tests were used to compare the clinical baseline and characteristics of patients. For continuous variables, Student's t-test and ANOVA were performed to evaluate statistical significance. Clinical outcomes were estimated by using the Kaplan‒Meier method and log-rank test. Furthermore, univariate and multivariate Cox regression models were utilized to analyze independent prognostic factors of ESCC patients. Results: Consequently, advanced ESCC patients were effectively stratified into two groups by prognosis using a PLNR cutoff value of 0.15 (P value = 0.04). The median survival time of patients with PLNR 45 mm (HR 1.32, 95 % CI 1.02–1.70), N stage (HR 1.41, 95 % CI 0.98–2.01) and PLNR ≥0.15 (HR 1.35, 95 % CI 0.87–1.74) were independent risk factors for prognostic prediction in ESCC patients. Meanwhile, 117 II∼III ESCC patients from Shaanxi Provincial People's Hospital shown that the overall survival with a PLNR