Lymph Node Ratio is an Independent Prognostic Factor in Node Positive Rectal Cancer Patients Treated with Preoperative Chemoradiotherapy Followed by Curative Resection

Background: The lymph node ratio (LNR) has been shown to be an important prognostic factor for colorectal cancer. However, studies focusing on the prognostic impact of LNR in rectal cancer patients who received neoadjuvant chemoradiotherapy (CRT) followed by curative resection have been limited. The aim of this study was to investigate LNR in rectal cancer patients who received neoadjuvant chemoradiotherapy (CRT) followed by curative resection. Materials and Methods: A total of 131 consecutive rectal cancer patients who underwent neoadjuvant CRT and total mesorectal excision were included in this study. Patients were divided into two groups according to the LNR (<= 0.2 [n=86], >0.2 [n=45]) to evaluate the prognostic effect on overall survival (OS) and disease-free survival (DFS). Results: The median number of retrieved and metastatic lymph node (LN) was 14 (range 1-48) and 2 (range 1-10), respectively. The median LNR was 0.154 (range 0.04-1.0). In multivariate analysis, LNR was shown to be an independent prognostic factor for both overall survival (hazard ratio[HR]= 3.778; 95% confidence interval [CI] 1.741-8.198; p=0.001) and disease-free survival (HR=3.637; 95% CI 1.838-7.195; p<0.001). Increased LNR was significantly associated with worse OS and DFS in patients with <12 harvested LNs, and as well as in those >= 12 harvested LNs (p<0.05). In addition, LNR had a prognostic impact on both OS and DFS in patients with N1 staging (p<0.001). Conclusions: LNR is an independent prognostic factor in ypN-positive rectal cancer patients, both in patients with <12 harvested LNs, and as well as in those >= 12 harvested LNs. LNR provides better prognostic value than pN staging. Therefore, it should be used as an additional prognostic indicator in ypN-positive rectal cancer patients.