Risk factors of lymph node metastasis in patients with non‐small cell lung cancer ≤ 2 cm in size: A monocentric population‐based analysis

AIM This study was designed to determine the risk factors of lymph node metastasis in non-small cell lung cancer (NSCLC) patients with tumors ≤ 2 cm, using the Shanghai Chest Hospital Lung Cancer Database. METHODS Five hundred and eighteen patients with NSCLC ≤ 2 cm were included in this study, and were classified into lymph node-positive and lymph node-negative groups. Univariate and multivariate logistic regression analyses were performed to select the independent risk factors for lymph node metastasis in NSCLC patients. RESULTS No evidence of metastasis was found in tumors ≤ 1 cm, all positive results were in tumors sized 1-2 cm. Imaging characteristics, including solid and part-solid nodules, were strongly associated with lymph node metastasis (odds ratio [OR] 24.959, 95% confidence interval [CI] 5.999-103.835, P < 0.001; OR 12.559, 95% CI 3.564-44.259, P < 0.001) and subgroup logistic analysis (OR 21.384, 95% CI 5.058-90.407, P < 0.001; OR 11.632, 95% CI 3.290-41.126, P < 0.001). Greater lymph node metastasis was observed in non-adeno non-squamous carcinoma. The presence of pleural invasion and carcinoembryonic antigen levels indicated lymph node dissection. Similar results were revealed in subgroup analysis in tumors ≤ 2 to > 1 cm. CONCLUSION Size had a great impact on lymph node metastasis, especially tumors of 1-2 cm. Preoperative imaging, non-adeno non-squamous carcinoma, pleural invasion, and carcinoembryonic antigen all indicated lymph node dissection. There was no discrepancy between N1 and N2 positive lymph nodes.