Lymph Node Evaluation and Survival in Colorectal Cancer: Review of Population-based, Prospective Studies

Aim: The total number of lymph nodes retrieved, the number of positive nodes, and/or their ratio are used to evaluate the degree of progression of colorectal cancer. The aim of the present study is to review the relevant literature in order to improve lymph node evaluation and the quality of clinical practice. Materials and Methods: The English language literature on large, population-based, prospective clinical studies of the evaluation of lymph nodes in colorectal cancer was reviewed. This review focuses on the lymph node harvest (LNH) and the lymph node ratio (LNR), and the survival was also assessed. Results: The LNH was influenced by patient age, tumor size, Dukes' stage, preoperative radiotherapy, operative urgency, specimen length, pathology template, and academic status of the hospital. Many prospective studies demonstrated a significant correlation between high LNH and increased survival. LNR is an independent prognostic indicator for stage III colorectal cancer. However, there were many different cut-off values allowing for the optimal separation of subgroups according to survival. Conclusion: To improve lymph node evaluation and the quality of clinical practice, daily collaboration between surgeons and pathologists is important. Scientific evidence for reasonable and practical LNH and LNR values should be identified based on large, well-controlled, prospective studies.