| [ Summary ] |
Assessment of the depth of submucosal invasion of endoscopically resected early colorectal cancers is one of the most important factors in determining whether additional radical surgery is required. Heretofore, histological classifications in Japan for the assessment of the depth of submucosal cancer invasion has adopted the muscularis mucosae as a standard line. However, the muscularis mucosae usually shows deformities and is destroyed in accordance with cancerous invasions and finally completely disappears. None of the classifications make clear assessments possible in such cases.
In our classification, the depth of submucosal cancer invasion is estimated by using the border of the lamina propria of the mucosa and the submucosal layer as the standard line, determined not only by the muscularis mucosae but also by considering other histological findings, such as the tubular arrangement of neoplastic tissue, desmoplastic stromal reactions and the pattern of cancerous invasion. In examining 223 surgically resected submucosal cancers, in 16 % we were able to estimate the depth of the submucosal invasion using only the remnant muscularis mucosae as the standard line. In the rest of the cases (84 %), the muscularis mucosae was deformed or absent, so that the estimation could not be made if it was solely dependent on the muscularis mucosae. Examples were presented for the assessments of cases with various patterns of cancer invasion and deformities or the disappearance of the muscularis mucosae. |