Lymph Node Micrometastases in Lung Cancer

Lung cancer remains the most common cause of cancer-related death in Europe and the United States (9, 10). Nonsmall-cell lung cancer (NSCLC) affects approximately 80% of all lung cancer patients (5, 9). Surgery remains the gold standard treatment for locoregional NSCLC, and pathological lymph node (pN) status has remained the strongest clinical prognostic characteristic in early stages of operable NSCLC (21, 23). However, even in early stages, the 5-year survival rate of N0 patients remains at only 60–70% after complete resection of the primary tumor (7, 17). This suggests that tumor cell dissemination occurs early and occult micrometastases or single disseminated tumor cells (DTC), which are not discovered by conventional histopathologic methods, may be present in the lymph nodes at the time of surgery (6, 16, 18, 22, 26). Detection of these cells might potentially improve clinical lymph node staging and help to identify patients who could benefit from adjuvant or neoadjuvant therapy.