Prognostic Significance of the Number of Lymph Nodes Removed at Lobectomy in Stage IA Non-small Cell Lung Cancer

Abstract

Lobectomy with mediastinal lymph node dissection is the standard of care in stage IA non-small cell lung cancer (NSCLC). We investigated whether the number of lymph nodes removed influences survival in stage IA NSCLC patients who underwent lobectomy. 2545 stage IA NSCLC patients in the California Cancer Registry who underwent lobectomy between 1999 and 2003 were analyzed. Cox proportional hazards regression was used to identify independent prognostic factors. Increasing number of lymph nodes removed was associated with statistical significant improvements in overall survival (OS) (p = 0.0001) and lung cancer-specific survival (LCSS) (p = 0.0309) of stage IA NSCLC patients who underwent lobectomy. The number of lymph nodes removed remained an independent favorable prognostic factor for OS (ptrend = 0.0001) and LCSS (ptrend = 0.0095) even after adjustment for other independent prognostic factors including age, sex, histology, histologic grade, socioeconomic status, and marital status in the Cox proportional regression analyses. Removal of 11 to 15 lymph nodes conferred the lowest hazard ratio for death [versus none; hazard ratio = 0.52; 95% confidence interval: 0.36-0.75]. The number of lymph nodes removed in stage IA NSCLC patients who underwent lobectomy is an independent prognostic factor for OS and LCSS.