Abstract 1220P
Background
The current pathological nodal (pN) stage is incomplete for distinguishing heterogeneous pN1 and pN2 disease well for patients with non-small cell lung cancer (NSCLC). We performed a large retrospective study to incorporate the number of lymph nodes (nN) into TNM classification using data from the Surveillance Epidemiology and End Results (SEER) database and further validated its feasibility using data from Shandong Cancer Hospital and Shandong Provincial Hospital.
Methods
A training cohort of 5779 and 8231 NSCLC patients from the SEER database were collected in this study. Concurrently, a validation cohort of 385 NSCLC patients from Shandong Cancer Hospital and Shandong Provincial Hospital were also included. The X-tile model was used to determine the optimal cutoff value of nN. Kaplan-Meier and log-rank tests were used to compare survival differences. The multivariate Cox proportional hazards regression model was used to analyse the influence of pN staging on overall survival (OS).
Results
According to the optimal cutoff value of nN, we classified patients into three nN categories (nN0; nNa: nN1-4; nNb: nN4-). Data from the training cohort indicated that survival curves were better in patients with pN2a compared to those with pN1b (P < 0.001). The multivariate Cox analysis also revealed that patients with pN1b and pN2a had no significant difference in OS (pN2a VS. pN1b: HR=0.926; 95%CI: 0.774-1.109; P = 0.406). The modified TNM staging based on the location and number of lymph nodes was used for further analysis. Survival curves of modified pN1 and pN2 were well distributed compared with the current TNM staging in the training cohort (P < 0.001) and the validation cohort (P = 0.049).
Conclusions
The modified TNM staging combined locational pN stage and numerical nN stage and was a more accurate prognostic determinant in NSCLC patients.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.