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.