Estimation of the number of metastatic lymph nodes in dukes' C colorectal cancer.

BACKGROUND

Colorectal cancer staging is decided by the depth of tumor invasion and the node (N) category. Evaluation of the metastatic lymph node number (MLN) varies. The purpose of this study was to investigate the N-category as a function of MLN.

PATIENTS AND METHODS

Patients with colorectal cancer (n=551) who underwent curative resection were grouped based on the MLN, and appropriate cut-off values were decided based on survival. The validity of the new cut-off values was analyzed as a prognostic factor.

RESULTS

The median number of lymph nodes retrieved per patient was 19, and the median MLN was 2. The survival and recurrence rates allowed MLN groupings of 1-4, 5-7, and ≥8. In particular, when grouping was performed using MLN ≤4 and ≥5, the 5-year survival rate for patients with MLN ≥5 (56.8%) was significantly worse than that of these with MLN ≤4 (78.6%) (p<0.0001). Receiver operating characteristic (ROC) curve analysis showed the highest accuracy to be with MLN=5. Multivariate analysis using a Cox proportional hazard model identified MLN ≥5 as an independent adverse prognostic factor (hazard ratio=1.84; 95% confidence interval=1.2801-2.6295; p=0.0012).

CONCLUSION

MLN ≥5 is an independent predictor of 5-year survival for patients with Dukes' C colorectal cancer. It is possible that tumor staging in colorectal cancer differs between facilities, with particular ramifications for patients with stage III disease.