Tu1449 Potential Predictors of Lymph Node Metastasis in T1 Colorectal Cancer Based on Clinicopathological Findings: Significance of Poorly Differentiated Findings in the Infiltrated Region of a Tumor

Abstract

Potential Predictors of Lymph Node Metastasis in T1 Colorectal Cancer Based on Clinicopathological Findings: Significance of Poorly Differentiated Findings in the Infiltrated Region of a Tumor Yohei Terakado*, Akimichi Imamura Gastroenterology, Sapporo Kosei General Hospital, Sapporo, Japan Objective: To determine risk factors for lymph node (LN) metastasis in T1 colorectal cancer (submucosally invasive cancer). Methods: We reviewed 160 patients with colorectal cancer undergoing surgery with lymph node dissection, except for prior endoscopic therapy, at our hospital between January 2000 and October 2012. The endpoints were submucosal (SM) infiltration depth, vascular invasion, budding, poorly differentiated component in the infiltrated region of the tumor (POR), and poorly differentiated findings. The associations of these endpoints with LN metastasis were examined. A POR was defined as a cancer cell focus with a poorly formed glandular structure containing 5 or more cells with interstitial infiltration, and poorly differentiated findings were defined as findings with either budding or POR. Results: Of the 160 T1 cancer patients examined, 122 had SM massive cancer with an SM infiltration depth of at least 1000 mm, and 18 (11.3%) had LN metastasis. According to univariate analysis, the 18 patients with LN metastasis had significantly higher rates of vascular invasion (18/80 patients [22.5%] vs. 0/80 [0.0%], P 0.001), budding (11/49 [22.4%] vs. 7/118 [5.9%], P 0.003), POR (12/58 [20.7%] vs. 6/102 [5.9%], P 0.004), and poorly differentiated findings (15/69 [21.7%] vs. 3/91 [3.3%], P 0.001). There was no significant difference in the rate of SM massive cancer (17/ 122 [13.9%] vs. 1/38 [2.6%], P 0.054). Thus, SM infiltration depth did not predict LN metastasis. Multivariate analysis using these 5 factors identified only poorly differentiated findings (OR 4.69, 95% CI 1.23-17.83, P 0.023) as a significant risk factor. Conclusions: Poorly differentiated findings are a potential risk factor for LN metastasis in submucosally invasive CRC, suggesting that the indications for radical endoscopic resection should possibly be extended.