The positive lymph node ratio predicts long-term survival in patients with operable thoracic esophageal squamous cell carcinoma in China

Abstract

Background: Controversy exists concerning the optimal cutoff points for the positive lymph node ratio (PLNR) to predict overall survival. We aim to propose reasonable PLNR categories for the discrimination of the survival difference between groups.

Methods: We used data from two centers to establish a training (n = 1006) and a validation (n = 783) cohort. All of the patients underwent curative surgical treatment. Martingale residuals from a Cox proportional hazards regression model were used to determine the optimal cutoff points for PLNR to predict overall survival. The survival rate was calculated using the Kaplan-Meier method, and a log-rank test was used to assess the survival differences between groups. The results obtained from the training cohort were tested with the validation cohort at each step.

Results: We classified the patients into four revised nodal categories: R-pN0 (PLNR = 0), R-pN1 (0< PLNR ≤0.1), R-pN2 (0.1< PLNR ≤0.3), and R-pN3 (PLNR >0.3). Subgroup analysis for the pT2 and pT3 cases showed that the survival differences could be well discriminated between groups based on PLNR in both the training cohort and validation cohort. When we modified the current staging system using revised nodal categories (based on PLNR) instead of the AJCC nodal categories, the survival rate could also be easily distinguished between patients in different stages in both cohorts of patients.

Conclusions: The survival rate of ESCC can be discriminated between four groups: PLNR = 0, 0< PLNR ≤0.1, 0.1< PLNR ≤0.3, and PLNR >0.3. Further studies are required to confirm these results.