Risk factors for lymph node metastasis and surgical scope in patients with cN0 non-small cell lung cancer: a single-center study in China

BACKGROUND: It is difficult to determine the lymph node metastasis of patients with clinically negative lymph nodes (cN0) non-small cell lung cancer (NSCLC) before surgery. The purpose of this study is to investigate risk factors of lymph node metastasis in cN0 NSCLC, thereby to identify the surgical indications for lymph node dissection in cN0 NSCLC. METHODS: We conducted a retrospective study of patients with tumor size ≤ 30 mm who underwent radical resection of NSCLC. Binary logistic regression analysis was applied to predict risk factors for lymph node metastasis, and subject operating characteristics (ROC) curve was used to evaluate the independent risk factors. RESULTS: Overall, 44 patients (6.8%) with cN0 NSCLC had lymph node metastasis. Factors of tumor consolidation diameter (p < 0.001) and preoperative serum carcinoembryonic antigen (CEA) level (p = 0.017) are independent risk factors lymph node metastasis in cN0 NSCLC. The ROC curve showed that the cut-off value of consolidation diameter was 16.5 mm, and the area under the curve (AUC) was 0.825 (p < 0.001, 95% CI 0.780–0.870); the cut-off value of serum CEA level was 1.765 μg/L, and the AUC was 0.661 (p < 0.001, 95% CI: 0.568–0.754). Moreover, 8 of 461 patients with tumor parenchyma ≤ 16.5 mm had lymph node metastasis, and 36 of 189 patients with tumor parenchyma > 16.5 mm had lymph node metastasis. CONCLUSION: Tumor consolidation diameter and preoperative serum CEA are independent factors to predict cN0 NSCLC with tumor size ≤ 30 mm. For patients with tumor parenchyma > 16.5 mm, the probability of lymph node metastasis is higher and lymph node dissection is recommended. For patients with tumor parenchyma ≤ 16.5 mm, the probability of lymph node metastasis is lower and lymph node sampling is feasible.