Clinical significance of patterns of intrathoracic lymph node metastasis in non-small cell lung cancer: an analysis of 314 patients

Objective: To investigate the patterns of intrathoracic lymph node metastasis in non-small cell lung cancer (NSCLC) and to provide a theoretical basis for the delineation of radiotherapy target volume. Methods: A retrospective analysis was performed on the clinical data of 314 NSCLC patients after operation. Our focus was to investigate the distribution characteristics and metastatic extent of intrathoracic lymph nodes and their relationship with tumor size, pathological type, and primary site. Comparisons between groups were made by one-way analysis of variance. Results: The frequencies of metastases to lymph nodes at stations 4, 5, 7, 10, and 11 were all above 12%, while those at stations 1, 2, 3, 6, 8, and 9 were all below 12%. The lymph node metastasis rate was similar on the primary tumor site (P = 0.102). The patients with T₃ and T₄ NSCLC had a significantly higher frequency of N₂ lymph node metastasis than those with T₁ and T₂ NSCLC (17.0% vs. 11.6%, P = 0.002); the patients with adenocarcinoma had a significantly higher frequency of N₂ lymph node metastasis than those with squamous cell carcinoma (34.5% vs. 23.2%, P = 0.008). Conclusions: For patients with T₃ and T₄ NSCLC of adenocarcinoma subtype, we should highlight the lymph nodes at stations 4, 5, 7, 10, and 11 when delineating the radiotherapy target volume after operation. (authors)