Lymph node metastasis in small peripheral adenocarcinoma of the lung

Our aim in this study is to clarify the clinical and pathologic features of small peripheral adenocarcinoma of the lung with special emphasis on intraoperative identification of lymph node metastasis.

Between 1980 and 1996, 157 patients underwent lobectomy and complete hilar/mediastinal lymphadenectomy for small (1.1 to 2.0 cm in diameter) peripheral adenocarcinoma of the lung. The intraoperative assessment, the distribution of metastatic lymph nodes, and the association between the tumor's histopathologic characteristics and lymph node metastasis were retrospectively investigated in this study.

Postoperative examination revealed lymph node metastasis in 27 (17%) patients. Lymph node metastases were not noticed during the operation in 19 of these 27 patients. Metastases were localized in single lymph nodes in 10 patients; the metastases were distributed over a segmental, a lobar, an interlobar, and a mediastinal lymph node. The prevalence of lymph node metastasis was as follows: Of 92 patients with well-differentiated adenocarcinoma, seven (8%) had lymph node metastases; of the 65 patients with other types of tumors, 20 (31%) had lymph node metastases. Of 120 patients without pleural involvement, 13 (11%) had lymph node metastases; of the 37 with pleural involvement, 14 (38%) had lymph node metastases. Five-year survivals were estimated at 91% +/- 6% (mean +/- 95% confidence interval) for 130 patients with N0 tumor and 30% +/- 22% for 27 patients with N1 or N2 tumor.

Intraoperative assessment is not reliable for identifying lymph node metastasis. Lobectomy and complete hilar/ mediastinal lymphadenectomy are necessary to determine N stage rigidly. Histologic degree of differentiation and pleural involvement are significantly associated with lymph node metastasis.