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Abstract Objectives The 9th edition of the lung cancer tumor-node-metastasis (TNM) staging system downgrades certain non-small cell lung cancer (NSCLC) patients from stage IIIA (T1N2) to IIB. This study aimed to externally validate this stage adjustment. Methods Consecutive resected stage IIB and IIIA NSCLC patients were included. Subgrouping was done based on lymph node involvements: IIB N2a1 (single-station N2 without N1 involvement), IIB N2a2 (single-station N2 with N1 involvements) and IIB N0-1. Overall survival (OS) and disease-free survival (DFS) were compared using the Kaplan-Meier method, with propensity score matching (PSM) employed to mitigate potential biases. COX regression models were utilized to assess prognostic differences. Results 224 stage IIB and 227 stage IIIA cases was included. There were 38, 66 and 120 patients in the IIB N2a1, IIB N2a2 and IIB N0-1 subgroups, respectively. Univariate COX analysis indicated comparable prognoses between the stage IIB N0-1 and IIB N2a1 patients, whereas stage IIB N2a2 patients exhibited poorer outcomes. Upon combining the stage IIB N2a1 and IIB N0-1 subgroups, multivariate COX analysis demonstrated a significantly worse prognosis for stage IIB N2a2 patients compared to those with stage IIB N2a1/0–1 tumors (OS, P = 0.035; DFS, P = 0.021). Further comparisons between stage IIB N2a2 and IIIA patients, following PSM analysis, indicated similar survivals (OS: P = 0.390; DFS: P = 0.210). Conclusion The prognosis of stage IIB N2a2 patients was worse than that of remaining stage IIB patients but comparable to that of stage IIIA patients. We proposed that stage IIB N2a2 patients should be maintained as stage IIIA.
Wu et al. (Sun,) studied this question.