Lymph node metastasis and its risk factors in T1 lung adenocarcinoma

BACKGROUND: In this study, the focus was primarily on examining the occurrence of lymph node metastasis in T1 lung adenocarcinoma, while also analyzing the relationship between clinical variables such as imaging characteristics, pathological classifications, and lymph node metastasis. METHODS: We retrospectively analyzed data from patients with T1 lung adenocarcinoma who underwent lobectomy and lymph node dissection between January 2016 and December 2019. Utilizing univariate and multivariate analyses, we assessed the associations between lymph node metastasis and various clinical factors, including imaging characteristics, lesion location and depth, and pathological subtypes. RESULTS: Of the 433 patients with T1 lung adenocarcinoma, 139 had lymph node metastasis. Moreover, the incidence of node 1 (N1) lymph node, sequential, and node 2 (N2) skip metastases were 12.2%, 12.7%, and 7.2%, respectively. Univariate analysis revealed that tumor diameter, depth ratio, sex, invasive imaging features, and pathological subtype were significantly associated with lymph node metastasis. Multivariate analysis revealed that the tumor depth ratio, tumor diameter, pleural indentation or traction sign, nonvascular penetration sign, solid component, nonadherence, and micropapillary pathological subtype were risk factors for lymph node metastasis. In the multivariate analysis, the micropapillary pathological subtype was an independent risk factor for N2 skip metastasis. CONCLUSIONS: In patients with clinical stage T1 lung adenocarcinoma, the risk of lymph node metastasis is higher for tumors located deep within the lung tissue with solid components, invasive preoperative imaging features, and larger diameters. For N2 skip lymph node metastasis, the micropapillary pathological subtype represents a significant high‐risk factor.