Prognostic role of the lymph node ratio in node positive colorectal cancer: a meta-analysis

// Ming-Ran Zhang 1, 3, * , Tian-Hang Xie 2, * , Jun-Lin Chi 1, 3 , Yuan Li 3 , Lie Yang 1 , Yong-Yang Yu 1 , Xiao-Feng Sun 3, 4 , Zong-Guang Zhou 1, 3 1 Department of Gastrointestinal Surgery, West China Hospital, Sichuan University, Chengdu, China 2 Department of Orthopedics, West China Hospital, Sichuan University, Chengdu, China 3 Institute of Digestive Surgery and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China 4 Department of Oncology, Department of Clinical and Experiment Medicine, Linkoping University, Linkoping, Sweden * These authors contributed equally to this work Correspondence to: Zong-Guang Zhou, email: zhou767@163.com Keywords: colorectal cancer, lymph node, lymph node ratio, prognostic role, meta-analysis Received: March 01, 2016 Accepted: September 13, 2016 Published: September 20, 2016 ABSTRACT The lymph node ratio (LNR) (i.e. the number of metastatic lymph nodes divided by the number of totally resected lymph nodes) has recently emerged as an important prognostic factor in colorectal cancer (CRC). However, the tumor node metastasis (TNM) staging system for colorectal cancer does not consider it as a prognostic parameter. Therefore, we conducted a meta-analysis to evaluate the prognostic role of the LNR in node positive CRC. A systematic search was performed in PubMed, Embase and the Cochrane Library for relevant studies up to November 2015. As a result, a total of 75,838 node positive patients in 33 studies were included in this meta-analysis. Higher LNR was significantly associated with shorter overall survival (OS) (HR = 1.91; 95% CI 1.71–2.14; P = 0.0000) and disease free survival (DFS) (HR = 2.75; 95% CI: 2.14–3.53; P = 0.0000). Subgroup analysis showed similar results. Based on these results, LNR was an independent predictor of survival in colorectal cancer patients and should be considered as a parameter in future oncologic staging systems.