Clinical Significance of Lymph Node Micrometastasis in Patients with Stage I Non-Small Cell Lung Cancer

Choi, Phil Jo; Roh, Mee Sook; Lee, Jae Ik

Abstract

BACKGROUND: The prognostic significance of lymph node micrometastasis in non-small cell lung cancer remains controversial. We therefore investigated the clinicopathologic factors related to lymph node micrometastsis and evaluated the clinical relevance of micrometastasis with regard to recurrence. MATERIAL AND METHOD: Five hundred six lymph nodes were obtained from 41 patients with stage I non-small cell lung cancer who underwent curative resection between 1994 and 1998. Immunohistochemical staining using anticytokeratin Ab was used to detect micrometastasis in these lymph nodes. RESULT: Micrometastatic tumor cells were identified in pN0 lymph nodes in 14 (34.1%) of 41 patients. The presence of lymph node micrometastasis was not related to any clinicopathologic factor (p>0.05). The recurrence rate was higher in patients with micrometastasis (57.1%) than in those without (37.0%), but the difference was not significant (p=0.22). Patients with micrometastasis had a lower 5-year recurrence-free survival rate (48.2%) than those without micrometastasis (64.1%), with a borderline significance (p=0.11). The 5-year recurrence-free survival rate (25.0%) in the patients with 2 or more micrometastatic lymph nodes was significantly lower than that in the patients with no or single micrometastasis (p=0.02). In multivariate analysis, multiple lymph node micrometastasis was a significant independent predictor of recurrence (p=0.028, Risk ratio=3.568).
CONCLUSION
Immunohistochemical anti-cytokeratin staining was a rapid, sensitive, and easy way of detecting lymph node micrometastasis. The presence of lymph node micrometastasis was not significnatly associtated with the recurrence, but had a tendency toward a poor prognosis in stage I non-small cell lung cancer. Especially, the presence of multiple micrometastatic lymph nodes was a significant and independent predictor of recurrence.