Effect of Lymph Node Assessment on Outcomes in Surgery for Limited Stage Small Cell Lung Cancer.

Background: The National Comprehensive Cancer Network guidelines recommend surgery for limited stage small cell lung cancer (SCLC). However, there is no literature on minimum acceptable lymph node retrieval in surgery for SCLC.

Methods: The National Cancer Database was queried for adult patients undergoing lobectomy for limited stage (cT1-2N0M0) SCLC from 2004 to 2015. Patients with unknown survival, staging, or nodal assessment, and patients who received neoadjuvant therapy were excluded. The number of lymph nodes assessed was studied both as a continuous variable and as a categoric variable stratified into distribution quartiles. The primary outcome was overall survival and the secondary outcome was pathologic nodal upstaging.

Results: A total of 1051 patients met study criteria. In multivariable analysis, only a retrieval of eight to 12 nodes was associated with a significant survival benefit (hazard ratio 0.73; 95% confidence interval, 0.56 to 0.98). However, when modeled as a continuous variable, there was no association between number of nodes assessed and survival (hazard ratio 1.00; 95% confidence interval, 0.98 to 1.02). The overall rate of pathologic nodal upstaging was 19%. Modeled as a continuous variable, more than seven lymph nodes assessed at time of resection was significantly associated with nodal upstaging in multivariable regression (odds ratio 1.03; 95% confidence interval, 1.01 to 1.06).

Conclusions: In this study, there was no clear difference in survival based on increasing the number of lymph nodes assessed during lobectomy for limited stage SCLC. However, the number of retrieved lymph nodes was associated with pathologic nodal upstaging. Therefore, patients may benefit from retrieval of more than seven lymph nodes during lobectomy for SCLC.