RESUMO
T1 colorectal carcinomas (CRCs) are an initial site of metastatic spread. Various risk factors for lymph node metastasis have been investigated in T1 CRCs. However, the major step in the entire process of metastasis remains unclear. In terms of carcinoma invasion and metastasis, matrix metalloproteinases (MMPs) have recently gained increasing attention. Notably, MMP-7 is frequently overexpressed in CRCs, but its implication has not been determined in T1 CRCs yet. The present study aimed to clarify the associations between the pathological risk factors of T1 CRCs and MMP-7. In the current study, 211 lesions of T1 CRC that were resected endoscopically or surgically at Showa University Northern Yokohama Hospital (Yokohama, Japan) between April 2008 and December 2009 were retrospectively analyzed. MMP-7 was immunostained and evaluated by its frequency of expression. Pathological factors of T1 CRCs were analyzed in association with MMP-7 expression. Furthermore, the ultrastructural alterations of carcinoma invasion were examined using low vacuum-scanning electron microscopy (LV-SEM). MMP-7 expression was associated with venous invasion (P=0.005), and LV-SEM revealed the disappearance of the normal structure of collagen and elastic fibers of veins invaded by tumor cells expressing MMP-7. At the invasive front, MMP-7 has a vital role in carcinoma invasion, correlating with venous invasion of T1 CRCs.
RESUMO
Endoscopic treatment for early rectal cancer was investigated. The characteristics of early rectal cancer were compared with those of early colon cancer, and the advantages of endoscopic treatment were evaluated. The indications for endoscopic resection are mucosal cancer, slight submucosal invasion without vessel or lymphatic involvement, poorly differentiated adenocarcinoma, and sprouting. The presence of other characteristics indicates the need for surgical resection. Early rectal cancers in the form of laterally spreading tumors of the non-granular, pseudodepressed type should be treated with endoscopic submucosal dissection due to the high incidence of submucosal invasion. The decision on the procedure for the treatment of early rectal cancer may be complicated because of the anatomic character and function of the ano-rectal area, complications of anal dysfunction, and incidence of leakage from the anastomosis after surgery. A precise diagnosis after endoscopic examination based on the pit pattern with magnifying endoscopy may be an effective aid in selecting the most appropriate endoscopic treatment for early rectal cancer.