Effect of number of lymph nodes sampled on outcome in patients with stage I non-small-cell lung cancer.

We postulate that surgical sampling and pathologic evaluation of lymph nodes of surgical specimens from patients with stage I non-small-cell lung cancer (NSCLC) can have an effect on the time to recurrence and survival of these patients. We analyzed data on 442 patients with stage I NSCLC who were treated with surgical resection and some form of lymph node sampling. Associations between total lymph nodes sampled and disease-free survival (DFS) and overall survival (OS) were investigated. The effect of total lymph node stations sampled and the surgical techniques (random lymph node sampling, systematic sampling [SS], or complete mediastinal lymph node dissection [MLND]) on DFS and OS was also studied. Complete MLND and SS were defined as dissection or sampling of levels 4, 7, and 10 for right-sided lesions and levels 5 or 6 and 7 for left-sided lesions. Patients were divided into quartiles on the basis of total number of lymph nodes sampled. Improved DFS and OS were associated with greater number of lymph nodes sampled. SS and MLND were associated with improved survival compared with random lymph node sampling. The total number of lymph nodes sampled maintained strong significance in the multivariate analysis. These results indicate that examining a greater number of lymph nodes in patients with stage I NSCLC treated with resection increases the likelihood of proper staging and affects patient outcome. Such information is important not only for therapy and prognosis of individuals but also for identifying those who may benefit from adjuvant therapy.