Long-term results of pathological stage I non-small cell lung cancer: validation of using the number of totally removed lymph nodes as a staging control

Objective: The number of totally removed lymph nodes during thoracotomy was used alternatively to represent the quality of lymphadenectomy in patients with pathologic stage I non-small cell lung cancer (NSCLC). We combined this new parameter with other well-established prognostic factors and performed multivariate survival analyses to validate its usage as a stage control. Methods: Three hundred and twenty-one patients who underwent complete surgical resection for stage I NSCLC were reviewed retrospectively. Aside from the number of lymph nodes removed during thoracotomy, other well-known clinical and histopathological factors were also included as possible prognostic factors for analysis. Two survival analyses, overall death and cancer-related death as study end-point, were performed, using the Kaplan–Meier method and multivariable Cox's proportional hazard regression analysis. Stepwise method of variable selection was employed to choose the ‘best’ Cox proportional hazard model in each survival analysis. Results: The overall 5- and 10-year survival rates were 48 and 35%, and the cancer-related 5- and 10-year survival rate was 63.3 and 58.3%, respectively. The number of totally removed lymph nodes during thoracotomy, tumor size and smoking history in multivariable analysis significantly affected both overall and cancer-related survival rates. Cell type of adenocarcinoma or large cell carcinoma was associated with a worse cancer-related survival compared with other histological types. Conclusions: The quality of lymphadenectomy, represented quantitatively by the number of totally removed lymph nodes during thoracotomy, may impact on a more accurate tumor stage, and will affect the survival rate for patients with stage I NSCLC as well as other well known clinical and histopathological factors.