[Evaluation of early colorectal cancer with submucosal invasion based on histological architecture]

To clarify the clinicopathological features of tumors with submucosal invasion, especially superficial elevated and sessile ones, histological architectures of 32 cases of submucosal invasive cancers were analyzed. They were classified into 3 types based on cross-section view: PG and NPG of Shimoda's classification and PG'. Histological architectures were drawn in accordance with these findings. In 7 PG-Ca which consisted of PG only, no apparent correlation was found between the tumor sizes and invasion depth of submucosal layer. However, 12 NPG-Ca which consisted of NPG only and 12 Mixed-Ca which include various cross-section views both showed massive invasion into the submucosa with 1 cm or more in tumor size. Therefore these two types were similar in biological behavior in terms of invasion depth. And degree of submucosal invasion tended to increase in the order of PG-Ca, Mixed-Ca and NPG-Ca. Examinating histological architectures of the Mixed-Ca tumors in details, all of these cancers were consisted of both PG and PG'. Of the 12 Mixed-Ca, 91.7% were proved to be PG dominant type. Macroscopically, I s and II a contained 88.9% and 40.0% of Mixed-Ca, respectively. In conclusion, these results suggest that PG' is a subtype of PG, and PG-Ca have a correlation between tumor invasion and alteration from PG to PG' in histological architectures among submucosal cancers. It is important to clarify morphological features of PG' in margin of I s and II a tumors in diagnosing the depth of early colorectal cancers.