| [ Summary ] |
The concept and diagnosis of depressed-type colorectal tumors has been widely accepted, especially in Japan. However, the background of these tumors is uncertain. In this study, we examine the results of questionnaires reported on from 12 institutions in Japan. The results were as follows a total of 532 lesions, 455 depressed type colorectal tumors and 107 LST-NG (PD). The review character of depressed-type colorectal tumors and LST-NG (PD). As the result of this study, of depressed-type colorectal tumors showed the followings. i) They were likely to exist in the transverse and sigmoid colon, ii) Most were submucosal cancers, over 10 mm in size. iii) The incidence of lymph node metastasis was about 5 %. iv) The ratio of moderately differentiated adenocarcinoma was higher than other types of colorectal cancer. v) There was one case which exhibited liver matastasis, though the size of the tumor was only 10 mm. On the other hand, LST-NG (PD) exhibited the following. i) They were likely to exist in the ascending and transverse colon. ii) The ratio of submucosal cancer was about 40 %, regardless of tumor size. iii) The incidence of lymph node metastasis was about 1.9 %. v) There was no case which exhibited distant metastasis.
The common characteristic was that they tended to occur in middle-aged men and the incidence of synchronism multiple cancers was higher than that for general colorectal cancers. In the future, further studies will be needed to reveal a more certain background for depressed-type colorectal tumors. |