The yield of mediastinoscopy with respect to lymph node size, cell type, and the location of the primary tumor

Background: The aim of this study was to investigate the yield of cervical mediastinoscopy (CM) for pathologically diagnosed non-small cell lung cancer (NSCLC), with respect to lymph node size on computed tomography (CT), cell type, and the location of the primary tumor. Methods: We reviewed 142 patients who underwent standard cervical mediastinoscopy from April of 1994 to June of 2003 for pathologically diagnosed NSCLC. The staging yield was determined by the percentage of "positive" CM (metastatic paratracheal or subcarinal nodes). Mediastinoscopy was performed when the lymph node diameter was >1 cm and, since 200 1, whenever paratracheal or subcarinal lymph nodes were clearly seen on CT, regardless of size. Group A includes patients with lymph nodes on CT of : I cm. Group B includes patients with lymph nodes of <1 cm. The chi(2) test was used for statistical analysis. Results: We performed CM on 142 patients. There were 127 men (89.4%) and 15 women (10.6%). The mean age of the patients was 64.7 years (range, 38-83). The global yield was 28.2% (CM positive in 40 of 142 cases). The specific yield by groups was as follows, with respect to lymph node size: group A (lymph nodes >1 cm), 37.9%, and group B (lymph nodes <1 cm), 8.5% (p < 0.01). With respect to cell type, 16.3% were squamous tumors, 42.9% were adenocarcinomas (p < 0.01), 45.5% were large-cell carcinomas, and 44.4% were other types. With respect to the location of the primary tumor and T stage, there were no statistically significant differences (p = 0.09). When only patients with squamous tumors with no enlarged lymph nodes were considered, staging yield was 3.3% (one of 30), and 19.6% (20 of 102) of patients with a negative CM had positive mediastinal lymph nodes at the time of the resection. The yield was 9.8% (10 of 102 patients) in the territory accessible by CM at the time of the resection (true false negative), and 9.8% (10 of 102 patients) in the territory not accessible by CM. Conclusion: Lymph node size and cell type of primary tumors should be taken into account when selecting patients for staging with standard MC in NSCLC. In patients with squamous-type tumors with lymph nodes < I cm on CT, CM could be avoided because its low yield.