Influential factors on radiotherapy efficacy and prognosis in patients with secondary lymph node metastasis after esophagectomy of thoracic esophageal squamous cell carcinoma

Background The purpose of this study was to clarify whether pretreatment tumor burden-related index, including the gross tumor volume (GTV) of metastatic lymph nodes (VLN) and maximum diameter of metastatic lymph nodes (DLN), and inflammatory markers, consisting of neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR), are useful for assessing the therapeutic effects and prognosis with secondary lymph node metastasis (LNM) receiving chemoradiotherapy (CRT) or radiotherapy (RT) alone after resection of esophageal squamous cell carcinoma (ESCC). Patients and methods A total of 119 patients with secondary LNM after resection of ESCC were recruited and received curative RT only or CRT. The enrolled patients were grouped according to the median values of NLR, PLR, VLN, and DLN. The relationship between the responsiveness to treatment and these markers was analyzed by logistic analysis. The Kaplan-Meier method and log-rank test were adopted to calculate and compare the overall survival (OS) rates with these markers. The Cox models were used to carry out multivariate analyses. Results Univariate logistic regression analysis showed that the responses to treatment were highly associated with treatment method (P=0.011), NLR (P=0.000), PLR (P=0.003), VLN (P=0.000), and DLN (P=0.000). Next, multivariate logistic regression analysis showed that therapeutic method (hazard ratio [HR]=1.225, P=0.032), NLR (HR=2.697, P=0.019), and VLN (HR=4.607, P=0.034) were independent risk factors for tumor response. Additionally, Kaplan-Meier survival analysis of this cohort revealed that NLR (χ2 =27.298, P=0.000), PLR (χ2=16.719, P=0.000), VLN (χ2=48.823, P=0.000), DLN (χ2=40.724, P=0.000), and treatment methods (χ2=18.454, P=0.018) were significantly associated with OS. Furthermore, multivariate analysis was performed, and the results showed that therapeutic method (HR=1.223, P=0.048), NLR (HR=2.000, P=0.018), VLN (HR=2.379, P=0.020), and DLN (HR=2.901, P=0.002) were considered independent prognostic factors for OS. Conclusion This study found that NLR and VLN were promising as predictive markers for therapeutic effects, and NLR combined with VLN and with DLN might be useful biomarkers in predicting outcomes in patients with secondary LNM receiving CRT or single RT after esophagectomy.