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BACKGROUND AND AIM: In guidelines 2010 for the treatment of colorectal cancer from the Japanese Society for Cancer of the Colon and Rectum (JSCCR), the criteria for identifying curable T1 colorectal carcinoma after endoscopic resection were well/moderately differentiated or papillary histologic grade, no vascular invasion, submucosal invasion depth less than 1000 µm and budding grade 1 (low grade). We aimed to expand these criteria. METHODS: A total of 499 T1 colorectal carcinomas, resected endoscopically or surgically, were analyzed. Relationships between clinicopathologic findings and lymph node metastasis were evaluated. RESULTS: Lymph node metastasis was found in 41 (8.22%) of the 499 cases. The incidence of lymph node metastasis was significantly higher in lesions featuring poorly differentiated/mucinous adenocarcinoma, submucosal invasion ≥ 1800 µm, vascular invasion, and high-grade tumor budding than in other lesions. Multivariate logistic regression analysis showed all of these variables to be independent risk factors for lymph node metastasis. When cases that met three of the JSCCR 2010 criteria (i.e. all but invasion < 1000 µm) were considered together, the incidence of lymph node metastasis was only 1.2% (3/249, 95% confidence interval: 0.25-3.48%), and there were no cases of lymph node metastasis without submucosal invasion to a depth of ≥ 1800 µm. CONCLUSIONS: Even in cases of colorectal carcinoma with deep submucosal invasion, the risk of lymph node metastasis is minimal under certain conditions. Thus, even for such cases, endoscopic incisional biopsy can be suitable if complete en bloc resection is achieved.
Nakadoi et al. (Tue,) studied this question.