Prognostic significance of the metastatic lymph node ratio in node-positive rectal cancer.

BACKGROUND

The purpose of the study was to evaluate the prognostic value of metastatic lymph node ratio (LNR) in node-positive rectal cancer.

METHODS

A retrospective review was performed in 318 rectal cancer patients who received curative anterior resection in a single institution. Clinicopathological variables including LNR were studied in univariate and multivariate analyses by Cox regression. LNR was further studied when stratified by quartiles. Survival analyses were performed using the Kaplan-Meier method and log-rank test.

RESULTS

With median follow-up of 41 months, the 5-year disease-free survival (DFS) rate, overall survival (OS) rate, and local recurrence (LR) rate were 56.82%, 59.8%, and 11%, respectively. Multivariate analysis revealed that LNR as a continuous variable was the most significant prognostic factor for DFS, OS, and LR. On quartiles, LNR was stratified into three groups: <0.14, 0.14-0.49, and 0.5-1. The 5-year DFS rate was 72.57%, 58.54%, and 34.75% (P = 0.0001) and the 5-year OS rate was 72.19%, 61.92%, and 38.47% (P = 0.002) in the three groups, respectively. Five-year LR rate was significantly higher with LNR between 0.14 and 1 (3.6% in LNR<0.14 versus 15.6% in LNR 0.14-1, P = 0.019).

CONCLUSIONS

LNR is an important prognostic factor for node-positive rectal cancers. With a cutoff of 0.14 and 0.5, node-positive rectal cancer patients could be categorized into three subsets with significant different outcomes.