Incidence of mediastinal node involvement in clinical T1 bronchogenic carcinomas.

The incidence of mediastinal node involvement of T1 non-small-cell bronchogenic carcinomas was determined in 262 patients for the period June 1981 to January 1986. All patients underwent mediastinoscopy as part of their evaluation. Thirty-five patients (13%) had clinical primary T1 lesions. There were 17 adenocarcinomas, 10 squamous cell carcinomas, 6 large-cell anaplastic carcinomas and 2 bronchoalveolar carcinomas. Five patients had node involvement at mediastinoscopy: two had large-cell anaplastic carcinomas and one was a squamous cell carcinoma. Thoracotomy in the remaining 30 patients revealed 2 with pleural metastases, 1 with left upper lobe adenocarcinoma with metastases to the subaortic nodal area (not assessed by cervical mediastinoscopy). The other patients underwent resection, for a resectability rate of 90%. Therefore the overall incidence of mediastinal node involvement in this series was 17% (6 of 35) and was found to be highest among patients with large-cell anaplastic carcinomas (2 of 6), followed by adenocarcinomas (3 of 19) and squamous cell carcinomas (1 of 10). The larger number of large-cell anaplastic carcinomas in this series probably accounts for the higher incidence of N2 disease found compared with that of previous studies in the literature. Accordingly, preoperative mediastinal staging is recommended for all T1 large-cell anaplastic carcinomas and adenocarcinomas and for suspicious lesions of undetermined histology.