Influence of Extent of Lymph Node Evaluation on Survival for Pathologically Lymph Node Negative Non–Small Cell Lung Cancer

Objectives: Despite previous retrospective reports that the number of lymph nodes resected at curative intent surgery for lung cancer correlates with overall survival (OS), no consensus exists regarding the minimal nor optimal number of lymph nodes to resect at curative lung cancer surgery. Methods: We studied subjects in the Surveillance Epidemiology and End Results Database (SEER) diagnosed with non–small cell lung cancer between 2000 and 2011 who underwent either lobectomy or pneumonectomy and had pathologic negative nodal evaluation. We excluded patients with sublobar resection and/or no lymph node evaluation. We examined associations between number of lymph nodes evaluated and OS/lung cancer-specific survival by multivariable Cox regression; and predictors of evaluation of more lymph nodes. Results: Among the 33,463 patients in our sample, a median of 7 lymph nodes were evaluated. We found that lung cancer-specific survival and OS improved with increasing lymph node evaluation up to 16 to 18 lymph nodes (hazard ratio, 0.77 [95% confidence interval, 0.70-0.85] and 0.78 [95% confidence interval, 0.72-0.86], respectively). There was little additional improvement in outcomes with evaluation of >16 to 18 lymph nodes. Blacks, Hispanics, females, and patients from distinct geographical regions were less likely to have 16 or more lymph nodes evaluated. Conclusions: There was a consistently increasing survival benefit associated with a more extensive lymph node evaluation at lung cancer resection, up to 16 to 18 lymph nodes removed. The median number of nodes evaluated was, however, only 7, suggesting that setting a goal of ≥16 examined lymph nodes may lead to improved survival outcomes, and reduce disparities in care.

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