Preoperative mediastinoscopic assessment of N factors and the need for mediastinal lymph node dissection in T1 lung cancer.

The significance of preoperative N factor assessment in T1 lung cancer and the need for mediastinal node dissection in T1 N0 M0 cases were investigated. The results of mediastinoscopy were evaluated in patients with T1 adenocarcinoma or squamous cell carcinoma who underwent preoperative mediastinoscopy and thoracotomy from 1971 to 1991 (n = 164). Mediastinoscopy gave true negative results in 90% of patients, false negative in 1%, and true positive in 9%. The 5-year survival was 90% for patients with T1 N0 M0 disease who underwent nonradical dissection (n = 64) and 70% for those who underwent radical dissection (n = 61), indicating that the prognosis was significantly better (p < 0.05) with nonradical dissection. Distant metastasis was a common cause of death, and no death was related to local recurrence, whether nonradical or radical dissection had been performed. The results strongly suggest that preoperative mediastinoscopy and intraoperative node sampling are sufficient for assessment of N factors in T1 lung cancer. The possible relation between immunologic functional changes associated with mediastinal lymph node dissection and the prognosis in patients without evidence of positive lymph nodes should be clarified by a prospective randomized study.