[Preoperative staging in T1 and T2 lung cancers by mediastinoscopy and mediastinal lymph node dissection].

Between 1975 and 1992, mediastinoscopy and thoracotomy were performed on 184 T1 and 271 T2 lung cancer cases consisting of adenocarcinoma and squamous cell carcinoma. Mediastinoscopy gave true negative findings in 90.8% of the T1 patients, true positive findings in 7.6% and false negative findings in 1.6%. The comparable rates were 76.7%, 17.0% and 6.3% in T2 patients. The 5-year survival rate was 91.3% for T1N0M0 patients (n = 64) who underwent non-radical dissection (= NRD), and 69.4% for those (n = 70) who underwent radical dissection (= RD). The rate with NRD was significantly better (p < 0.006). The 5-year survival rate was 63.2% for T2N0M0 patients (n = 62) undergoing NRD, and 49.8% for those (n = 72) undergoing RD, but the difference was not significantly. Distant metastasis was a common cause of death, whereas there were no deaths due to local recurrence in the T1N0M0 patients, whether NRD or RD was performed. These results support our opinions that preoperative mediastinoscopy and intraoperative node staging are sufficient for assessment of the N factor in T1 and T2 lung cancer, and that mediastinal node dissection should not be performed in T1N0M0 patients.