Abstract
A total of 740 colorectal cancers have been treated at our hospital during the past five years (early cancer: 422 ; advanced cancer: 318) . In order to find treatment methods for colorectal cancer with submucosal invasion (sm cancer), we evaluated the clinicopathological features and lymph node metastasis of 114 cases of sm cancer. Lymph node metastasis was found in 10.0% of this series. The presence of lymphatic vessel permeation and massive cancer invasion into the submucosal layer were each significant risk factors for lymph node metastasis. In the patients whose histology at the front of the submucosal invasion showed moderately or poorly differentiated adenocarcinoma, lymph node metastasis tended to be more frequently observed ; however, this difference was not significant. Among the colorectal cancer patients who had none of the three factors, that is, those who did not have massive cancer invasion, lymphatic vessel permeation nor histology of moderate or poor differentiation at the invasive front, none had lymph node metastasis and we assumed that additional surgery was not necessary. Among the patients who had colorectal cancers with two or three of the three factors, the percentage of cases with lymph node metastasis was high (18.9%), and we felt that additional surgery including lymph node dissection was necessary. Among those who only had massive submucosal invasion and were negative for the other two risk factors, only one case (5.9%) had lymph node metastasis. In this case, the absolute depth of the vertical invasion below the muscularis mucosae was approximately 3, 000 μm. None of the cases with submucosal invasion less than 1, 750μm had lymph node metastasis. It was considered that additional surgical bowel resection was not necessary for those cases with submucosal invasion less than 1, 000 μm and who were negative for the other two risk factors.
