Predictive Factors for Lymph Node Metastasis in Submucosal Invasive Colorectal Carcinoma: A New Proposal of Depth of Invasion for Radical Surgery

Background: Patients with lymph node metastasis (LNM) in submucosal invasive colorectal carcinoma (SM cancer) require additional surgical treatment after endoscopic dissection. However, because additional radical resection after endoscopic local resection may be unnecessary for cases without LNM, more specific criteria are required in order to diminish the incidence of further radical resection after endoscopic dissection. Methods: A total of 492 patients with biopsy-proven SM cancer who underwent curative surgery between January 2008 and December 2012 were collected and were divided into LNM group and no LNM group. The cutoff value for the depth of submucosal invasion was analyzed by a receiver operating characteristic (ROC) curve. In this retrospective study, the association between LNM and clinicopathologic factors was analyzed by logistic regression analysis. Results: The depth of submucosal invasion of 1900 μm was determined as the cutoff value by ROC curve. Significant, independent predictive factors for LNM included the depth of submucosal invasion >1900 μm (odds ratio [OR] 7.5; 95% confidence interval [CI] 3.1–18.3; p < 0.001), venous invasion (OR 2.4; 95% CI 1.1–5.5; p = 0.03), and poorly differentiated/mucinous adenocarcinoma (OR 6.3; 95% CI 1.3–30.8; p = 0.02). Conclusions: Our study demonstrates that the depth of submucosal invasion (>1900 μm), vascular invasion and poorly differentiated/mucinous carcinoma were predictive factors of LNM in patients with SM cancer. These predictors may help to reduce the incidence of unnecessary surgery after endoscopic resection.