Background: The prognostic role of the number of resected lymph nodes (nLNs) in pathologic N0 (lymph node negative) and Nx (no lymph node examined) non-small cell lung cancer (NSCLC) patients remains uncertain. Guidelines for optimal nLNs have not been established. In the current study, we evaluated whether a higher number of resected lymph nodes (LNs) results in better survival in different tumor size categories among NSCLC patients without metastatic LNs.
Method: A retrospective study was conducted. Based on nLNs (LN = 0, 1-7, >7) and tumor size (Ta: ≤ 3.5 cm, Tb: >3.5 cm) during surgery, patients were categorized into 6 groups (LN0Ta, LN0Tb, LN1-7Ta, LN1-7Tb, LN7-Ta and LN7-Tb). Survival and multivariate analyses were carried out to determine whether nLNs combined with tumor size was significant for overall survival (OS) or disease free survival (DFS) after adjusting for potential confounders.
Results: A total of 428 patients were enrolled in the study. Multivariate analysis demonstrated that nLNs, tumor size and pathological stage were the independent prognosticators for OS and DFS. Data from our study suggested that lung cancer lymphadenectomy with more than 7 LNs removed should be considered a benchmark for surgery or pathology at an early stage. Survival was significantly better in the LN7-Ta group, compared with other 5 groups (p<0.001).
Conclusions: The combined predictor (nLNs combined with tumor size) is an independent prognostic factor and a reasonable stratification criterion in patients with pathologic N0 and Nx NSCLC. The validation of our finding is warranted in further investigation.