Background/aims: According to Japanese guidelines for early invasive (pT1) colorectal cancer, on histological examination of an endoscopic excision specimen, the most important predictive histopathologic factors for lymph node metastases are as follows: (i) depth of submucosal invasion (Vsm) is greater than 1000 microm, (ii) poorly differentiated adenocarcinoma or undifferentiated carcinoma, (iii) lymphatic or vascular invasion positive.
Methodology: A total of 111 early invasive colorectal cancer patients underwent surgery and their records were analyzed. The greatest depth, the greatest width, and the area of the submucosal invasion were measured. Histological type, histological type at the point of deepest invasion, lymphatic invasion, venous invasion, and "Tumor budding" were investigated using hematoxylin and eosin-stained specimens.
Results: Two histopathologic parameters had a significant influence on lymph node metastasis: histological type at the deepest part and "Tumor budding" (p = 0.041 and 0.001 respectively). These parameters are especially true when lymph node metastasis positive cases are compared with negative cases; it has little to do with having a Vsm less than 1000 microm or more than 1000 microm.
Conclusion: We emphasize that it is not important to find Vsm > or = 1,000 microm in order to find lymph node metastasis in submucosal invasive colorectal carcinomas.