Impact of Lymph Node Count versus Lymph Node Ratio (LNR) on Survival Analysis in UICC Stage III Colorectal Cancer

Background: Lymph node status is an important prognostic factor in curative oncologic colorectal surgery. An inadequate number of lymph nodes may result in under-staging with consequences on therapeutic and prognostic effects. The aim of our study was to evaluate the impact of total lymph node count (LNC) in comparison to the lymph node ratio (LNR) on overall (OAS) and disease specific survival (DSS) in UICC stage III colorectal cancer.

Methods: Data were collected prospectively within an audit-proof proprietary colorectal cancer database. The cutoff point of LNC was chosen as 12 because of current guidelines recommendation to assess a minimum of 12 lymph nodes in colorectal surgery. The cutoff point of LNR was chosen as 0.15 because of significant survival difference at that LNR.

Results: Of the 185 UICC stage III patients with colorectal cancer, 115 (62%) were localized in the colon and 70 (38%) in the rectum. Five-year OAS and DSS were statistically not significant in the LNC group (OAS: LNC <11=56%, LNC ≥12=80%, P=0.06 and DSS: LNC <11=64%, LNC ≥12=87%, P=0.07). In the LNR group with a cutoff point of 0.15 there was no statistically significant longer OAS (LNR ≤0.15=86%, LNR >0.15=67%, P=0.08). But the evaluation revealed a statistically significant longer DSS in LNR ≤0.15 (P=0.03).

Conclusion: LNR should be considered as a predictor value for survival analysis in colorectal surgery.