Comparison of metastatic lymph node ratio staging system with the 7th AJCC system for colorectal cancer.

Purpose: To evaluate the prognostic value and staging accuracy of the metastatic lymph node ratio (rN) staging system for colorectal cancer. Methods: A total of 1,127 patients with colorectal cancer who underwent curative surgery between 2000 and 2011 at our institute were analyzed. Lymph nodes status was assigned according to American Joint Committee on Cancer (AJCC) pN system and rN system. Patients with colon cancer (group 1, n = 652) and rectal cancer (group 2, n = 475) were analyzed separately. Results: The rN staging system was generated using 0.2 and 0.6 as the cutoff values of lymph node ratio and then compared with AJCC pN stages. Linear regression model revealed that the number of retrieved lymph node was related to number of metastatic lymph nodes. After a median follow-up of 46 months, the 5-year survival rates of patients with more than 12 lymph nodes (LNs) retrieved were better than cases with fewer than 12 LNs, while the differences were not obvious in rN classification. Conclusions : The rN category is a better prognostic tool than the AJCC pN category for colorectal cancer patients after curative surgery. [ABSTRACT FROM AUTHOR]