Mediastinal Lymph Node Examination and Survival in Resected Early-Stage Non-Small-Cell Lung Cancer in the Surveillance, Epidemiology, and End Results Database

Background: Pathologic nodal stage is the key prognostic factor in resectable non-small-cell lung cancer (NSCLC). Mediastinal lymph node (MLN) metastasis connotes a poor prognosis. Yet, some NSCLC resections exclude MLN examination. Methods: We analyzed U.S. Surveillance, Epidemiology, and End Results program data from 1998 to 2002 to quantify the long-term survival impact of failure to examine MLN in resected NSCLC. We used Kaplan-Meier methods to compare the unadjusted survival difference between patients with, and without, MLN examination, and Cox proportional hazards and competing risk models to serially adjust for the impact of risk factors on survival differences. Results: Sixty-two percent of patients with pathologic N0 or N1 NSCLC had no MLN examined. Overall 5-year survival rates were 52% for those with, versus 47% for those without, MLN examination; lung cancer-specific survival rates were 63% versus 58% respectively (p < 0.001); nonlung cancer mortality was identical between cohorts. Adjusting for potential confounders, MLN examination was associated with a 7% reduction in all-cause mortality (hazard ratio, 0.93; confidence interval, 0.88-0.97; p = 0.002), and 11% reduction in lung cancer-specific mortality (hazard ratio, 0.89; 95% confidence interval, 0.84-0.95; p < 0.001) rates. The excess risk in 1 year's cohort of U. S. lung resections was 3150 lives over 5 years. Conclusions: Failure to examine MLN was a common practice in MLN-negative NSCLC resections, which significantly impaired long-term survival. Efforts to understand the etiology of this quality gap, and measures to eliminate it, are warranted.