CT evaluation of mediastinal lymph nodes in lung cancer: influence of the lobar site of the primary neoplasm.

Previous reports have shown differences in the ability of CT to detect mediastinal lymph nodes, depending on the precise mediastinal location of the nodes. Poorest correlation between findings on CT and findings at autopsy has been described for left-sided lymph nodes, particularly those in the left peribronchial region (American Thoracic Society node station 10L), suggesting that cancers of the left lung might be less well staged by CT than cancers of the right lung. The relationship between the accuracy of mediastinal lymph node staging and the location of the primary lung cancer was examined in a retrospective study. In 103 patients with non-small-cell bronchogenic carcinoma who had preoperative CT evaluation of the mediastinum, the accuracy of preoperative staging was 81% for tumors of the right lung (70 patients) and 97% for tumors of the left lung (33 patients). The conclusion is that cancers of the left lung are staged at least as accurately as cancers of the right lung, despite the fact that left-sided mediastinal nodes are depicted more poorly on CT. Subcarinal and crossover (contralateral) nodal metastases and a low prevalence of metastasis involving only region 10L were the most important factors minimizing staging differences based on the site of the primary tumor.