Clinical predictors of N2 disease in non-small cell lung cancer

To identify clinical or radiologic predictors of mediastinal lymph node involvement in patients with non-small cell lung cancer, and to define the indications of preoperative mediastinoscopy.

From August 1992 through April 1997, 387 patients with lung cancer (290 adenocarcinoma and 97 squamous cell carcinoma) underwent surgical resection. We retrospectively measured all mediastinal lymph node sizes both in the shortest and longest axes on contrast-enhanced CT scan to determine the optimal size criteria. Using multivariate logistic regression analysis, we identified clinical or radiologic predictors of N2 disease.

We could not identify reliable size criteria for nodal involvement. We found two significant predictive factors of N2 disease on the basis of multivariable analysis: maximum tumor dimension and serum carcinoembryonic antigen (CEA) concentrations. The lymph node size did not prove to be a significant factor. Among 50 patients with serum CEA concentrations < 5.0 ng/mL and maximum tumor dimension < 20 mm, pathologic N2 disease was proven only in three patients (6%), regardless of the lymph node size on CT scan. Among 140 patients with serum CEA concentrations > or = 5.0 ng/mL and maximum tumor dimension > or = 20 mm, approximately one third (n = 46) showed N2 disease.

Serum CEA concentrations and maximum tumor dimension were more valuable in predicting N2 disease than the lymph node size on CT scan. Mediastinoscopy is indicated in patients with serum CEA concentrations > or = 5.0 ng/mL and maximum tumor dimension > or = 20 mm, and not indicated in patients with serum CEA concentrations < 5.0 ng/mL and maximum tumor dimension < 20 mm.