Lymph Node Positivity Is Associated with Survival in Metastatic Colorectal Cancer

INTRODUCTION: Lymph node positivity (LNP) is the strongest determinant of survival in localized CRC. In stages I to III, a decreased ratio of metastatic to examined nodes is associated with improved survival. However, LNP has not been studied in metastatic disease. This study aims to examine the correlation between LNP and survival in metastatic colorectal cancer (CRC). METHODS: We performed a retrospective review of the National Cancer Database of patients who underwent surgery for metastatic CRC between 2010 and 2014. Confounders considered included neoadjuvant therapy (NAT), age at diagnosis, liver resection, and tumor size. Kaplan-Meier curves were used to compare the median survival between node-positive and node-negative disease. Cox proportional hazard ratios and odds ratios were used to analyze the association between LNP and other variables. RESULTS: Our cohort of 25,114 patients (13,859 male; 11,264 female; median age at diagnosis, 63 years) included 5,636 patients with node-negative disease and 19,478 with node-positive disease (27.8% and 23.4% underwent liver resections, respectively). LNP was associated with NAT (odds ratio [OR] 0.55, 95% CI 0.50–0.60, p<0.001). Survival was associated with LNP (hazard ratio [HR] 1.54, 95% CI 1.47–1.61, p<0.001), controlling for liver resection (HR 0.67, 95% CI 0.64–0.70, p<0.001) and NAT (HR 0.56, 95% CI 0.53–0.60, p<0.001) (Figure).Figure: No Caption available.CONCLUSIONS: In metastatic CRC, LNP is associated with a decreased overall survival. Meanwhile, liver resection and NAT are associated with an improved survival. NAT is associated with decreased LNP, which might suggest that NAT can sterilize lymph nodes. However, our multivariate model showed that LNP could be independently predictive of overall survival, and that NAT sterilization is not the sole explanation for its prognostic value.