Qingguo Li¹, Sanjun Cai¹, Ye Xu¹, Huixun Jia², Ji Zhu³

¹Department of Colorectal Surgery, Fudan University Shanghai Cancer Center, ²Center for Biomedical Statistical, Fudan University Shanghai Cancer Center, ³Department of Radiation Oncology, Fudan University Shanghai Cancer Center.

Objective:Our aim was to determine impact of negative to positive lymph node ratio (NPR) on oncological outcomes in a series of patients with stage III colorectal cancer. Method: This retrospective study included 2,256 patients with stage III colorectal cancer under curative resection at Fudan university Shanghai cancer center from January 2007 to December 2012. Kaplan-Meier methods were adopted and multivariable Cox regression models were built for the analysis of long-term survival outcomes and risk factors. Result: X-tile program identified 6 and 2.38 as the optimal cutoff value for negative lymphnodes (NLN) and NPR to divide the cohort into high and low risk subsets interms of colorectal cancer cause specific survival (CCSS). In a multivariate analysis, NPR and NLN were significant independent prognostic factors for CCSS (P<0.05), notably, N classification was not an independently prognostic factor (P=0.883).Further analysis found NPR could stratified both N1 and N2 stage to high and low risk well (P<0.05).Conversely, N stage couldn't stratified NPR group (P>0.05).Interestingly, patients in N2+ NPR>2.38 stage have similar survival outcome with N1+ NPR>2.38 stage (χ²=0.030, P=0.863), and better than those at N1+ NPR ≤2.38 and N2+ NPR ≤2.38 stage (P<0.001).The different between N1+ NPR ≤2.38and N2+ NPR ≤2.38 stage was also not significance (χ²=0.290, P=0.590).Conclusion: NPR was an independent prognostic factor for stage III CRC patients, it could provide more accurate prognostic information than the current node stage system.

Key Words: Colorectal Cancer  Prognosis analysis  Lymph node