Influences of the size of lymph node metastasis on the chemoradiotherapy efficacy and prognosis for the patients after esophagectomy of thoracic esophageal squamous cell carcinoma

Objective To evaluate the effects of the size of lymph node metastasis (LNM) on the chemoradiotherapy efficacy and prognosis for the patients after resection of thoracic esophageal squamous cell carcinoma (ESCC). Methods Between 2011 and 2014, a total of 75 esophageal squamous carcinoma patients with secondary LNM after resection of ESCC were recruited in this retrospective study. They were treated with curative radiotherapy only or concurrent chemoradiotherapy in the Affiliated Taixing People′s Hospital of Yangzhou University. The LNM volume and maximum diameters were measured by the Monaco treatment planning system. The enrolled patients were grouped according to the median values of LNM volume and maximum diameters. The relationship between the responsiveness to treatment and these markers was analyzed by univariate and multivariate 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 proportional hazards model was used to carry out univariate and multivariate analyses. Results The overall effective rate was 69.3% for all enrolled patients. The response rates were 81.6% with LNM volume <57 cm3 and 56.8% with LNM volume ≥57 cm3. The response rates were 83.8% with LNM maximum diameter <5 cm and 55.3% with LNM maximum diameter ≥5 cm. The responses to treatment were highly associated with treatment method (OR=1.825, 95%CI: 1.134-3.658, P=0.017), LNM volume (OR=4.183, 95%CI: 1.416-12.354, P=0.010) and maximum diameter (OR=3.374, 95%CI: 1.185-9.611, P=0.023) by univariate logistic regression analysis. Multivariate logistic regression analysis showed that therapeutic method (OR=1.225, 95%CI: 1.085-2.837, P=0.038) and LNM volume (OR=1.614, 95%CI: 1.003-3.025, P=0.048) were independent risk factors for tumor response. The median OS time of this cohort was 14 months, and the 1, 2 and 3 year OS rates were 60.7%, 25.3% and 20.1%, respectively. Kaplan-Meier survival analysis revealed that TNM stage (HR=2.039, 95%CI: 1.234-3.370, P=0.005), treatment methods (HR=1.858, 95%CI: 1.385-2.958, P=0.013), LNM volume (HR=2.642, 95%CI: 1.552-4.497, P<0.001) and LNM maximum diameter (HR=3.399, 95%CI: 1.939-5.958, P<0.001) were significantly associated with OS. Furthermore, multivariate Cox proportional hazard regression model analysis for OS was performed and the results showed that TNM stage (HR=2.023, 95%CI: 1.149-3.560, P=0.015), LNM volume (HR=2.055, 95%CI: 1.041-4.055, P=0.038) and maximum diameter (HR=1.910, 95%CI: 1.137-3.895, P=0.045) were considered as independent prognostic risk factors for OS. Conclusion LNM volume in ESCC patients with secondary LNM after esophagectomy has great values for predictive therapeutic effects and survival outcomes, and LNM maximum diameter has significant value for survival outcomes. Key words: Esophageal neoplasms; Lymphatic metastasis; Radiotherapy; Drug therapy; Prognosis