Risk Factors of Lymph Node Metastasis in Submucosal Invasive Colorectal Cancer

The risk factors for lymph node metastasis, which are important for designing therapeutic strategies, were investigated in patients with submucosal invasive colorectal cancer. Seventy patients with submucosal invasive colorectal cancer were included in this study. The patients were divided into two groups based on lymph node metastasis, i.e., 64 patients without nodal metastasis and 6 patients with nodal metastasis. Comparison of clinicopathological findings between the two groups showed that the occurrence of lymph node metastasis was associated with lymphatic invasion, histological heterogeneity, and histological types other than well-differentiated adenocarcinoma at the invasive margin of the cancer. The rate of lymph node involvement were 100% (2/2) in the patients with all three of these factors, 30.0% (3/10) in patients with two factors, respectively. Whereas, none of the patients without any of these factors had lymph node metastasis. From the results described above, the following three risk factors for lymphatic metastasis by submucosal invasive colorectal cancer were identified : 1) lymphatic invasion, 2) histological heterogeneity, and 3) histological types other than well-differentiated adenocarcinoma at the invasive margin