Risk Factors for Predicting Lymph Node Metastasis in Submucosal Colorectal Cancer

Objectives: The cornerstone of treating colorectal cancer (CRC) is generally a surgical resection with lymph node (LN) dissection. The tools for predicting lymph node metastasis (LNM) in submucosal (SM) CRC are useful to avoid unnecessary surgical resection. Methods: Retrospectively, we analyzed 526 consecutive patients with SM CRC who underwent surgical re-section at the Osaka International Cancer Institute, Osaka University Hospital, and Minoh City Hospital, Ja-pan, between 1984 and 2012. The Osaka International Cancer Institute group and the Osaka University Hospital group were randomly divided into a training set and a test set of 2:1. The prediction model was validated in Minoh City Hospital. Results: We partitioned patients using three risk factors involved in the presence or absence of LNM in SM CRC: lymphatic invasion (Ly), budding grade (BD) and the depth of submucosal invasion (DSI) (cut-off value 2789 mu m) that were significantly different in the multivariate analysis. As a result, a predictive model of "LNM <5%" when "Ly negative and DSI <2789 mu m" was evaluated. We similarly partitioned by DSI 3000 mu m as easy-to-evaluate values in clinical use. We developed the additional model for predicting LNM is 1.05%, that is, LNM <5%, when there are "Ly negative and DSI <3000 mu m." Conclusions: As a limitation, only patients who underwent surgical resection were included in this study. This predictive model could help clinicians and CRC patients decide on the additional surgery required af-ter endoscopic resection.