Patterns of Mediastinal Lymph Nodes Metastasis in Non-small Cell Lung Cancer according to the Primary Cancer Location / 대한흉부외과학회지

ABSTRACT

BACKGROUND: The presence of infiltrated mediastinal lymph nodes is a crucial factor for the prognosis of lung cancer. The aim of our study is to investigate the pattern of metastatic non-small cell lung cancer that spreads to the mediastinal lymph nodes, in relation to the primary tumor site, in patients who underwent major lung resection with complete mediastinal lymph node dissection. MATERIAL AND METHOD: We retrospectively studies 293 consecutive patients [mean age 63.0+/-8.3 years (range 37~88) and 220 males (75.1%)] who underwent major lung resection due to non-small cell lung cancer from January 1998 to December 2005. The primary tumor and lymph node status was classified according to the international TNM staging system reported by Mountain. The histologic type of the tumors was determined according to the WHO classification. Fisher's exact test was used; otherwise the chi-square test of independence was employed. A p-value <0.05 was considered significant. RESULT: Lobectomy was carried out in 180 patients, bilobectomy in 50, sleeve lobectomy in 10 and pnemonectomy in 53. The pathologic report revealed 124 adenocarcinomas, 138 squamous-cell tumors, 14 adenosquamous tumors, 1 carcinoid tumor, 8 large cell carcinomas, 1 carcinosarcoma, 2 mucoepidermoid carcinomas and 5 undifferentiated tumors. The TNM stage was IA in 51 patients, IB in 98, IIB in 41, IIIA in 71, IIIB in 61 and IV in 6. 25.9 % of the 79 patients had N2 tumor. Most common infiltrated mediastinal lymph node was level No.4 in the right upper lobe, level No. 4 and 5 in the left upper lobe and level No. 7 in the other lobes, but no statistically significant difference was observed. Thirty-six patients (12.3%) presented with skip metastasis to the mediastinum. CONCLUSION: Mediastinal lymph node dissection is necessary for accurately determining the pTNM stage. It seems that there is no definite way that non-small cell lung cancer spreads to the lymphatics, in relation to the location of the primary cancer. Further, skip metastasis to the mediastinal lymph nodes was present in 12.3% of our patients.