Pathologic N0 status in pulmonary adenocarcinoma is predictable by combining serum carcinoembryonic antigen level and computed tomographic findings.

OBJECTIVES: It is not clear whether lymphadenectomy has therapeutic benefit in non-small cell lung cancer management. To avoid unnecessary lymphadenectomy, we attempted to identify clinical or radiologic predictors of pathologic N0 disease in patients with peripheral adenocarcinoma.
METHODS: From August 1992 through April 1997, 269 consecutive patients with peripheral adenocarcinoma who underwent major lung resection and systematic lymph node dissection were enrolled in this study. We reviewed their contrast-enhancement computed tomographic scans and recorded the maximum dimension of tumors both on pulmonary (pDmax) and on mediastinal (mDmax) window setting images, the largest dimension perpendicular to the maximum axis on both pulmonary (pDperp) and mediastinal (mDperp) window setting images, and the size of all detectable hilar-mediastinal lymph nodes. We defined a new radiologic parameter, tumor shadow disappearance rate (TDR), which is calculated with the following formula: TDR = 1 - (mDmax x mDperp)/(pDmax x pDperp).
RESULTS: In multivariable analysis a lower serum carcinoembryonic antigen level and a higher tumor shadow disappearance rate were significant predictors of pathologic N0 disease. Lymph node size on computed tomographic scanning was not a significant predictor. Among 59 patients with a normal preoperative carcinoembryonic antigen level and a tumor shadow disappearance rate of 0.8 or more, 58 (98%) patients had pathologic N0 disease, and the other patient had pathologic N1 disease.
CONCLUSIONS: Mediastinal lymph node involvement was not found in patients with a normal preoperative serum carcinoembryonic antigen level and a tumor shadow disappearance rate 0.8 or more. The patients who meet these criteria may be successfully managed with major lung resection without systematic mediastinal lymphadenectomy.