Clinicopathological features and overexpression of matrix metalloproteinases in intramucosal gastric carcinoma with lymph node metastasis

Endoscopic mucosal resection, which has been widely accepted for the treatment of intramucosal gastric carcinoma (IMGC) because of the minimal invasiveness of the procedure and the sustained quality of life it provides, can only be used on the premise that the carcinoma has no lymph node metastasis. We evaluated the clinicopathological and biological features of IMGC with lymph node metastases in relation to matrix metalloproteinase (MMP) expression. Fifteen cases of lymph node metastasis-positive [n(+)] IMGC and 59 cases, of lymph node metastatic-negative [n(-)] IMGC were obtained. The expression of MMP-2 and MMP-9 was investigated with immunohistochemical methods. Clinicopathologically, n(+)-IMGCs were more likely to be of a larger size, to be of poorly differentiated odenocarcinoma, to have had lymphatic permeation [ly(+)], and to have ulcerations within the lesion compared to n(-)-IMGCs. The incidence of the positive expression of MMP-9 in n(+)-IMGCs (67%) or ly(+)-IMGCs (86%) was significantly higher than that in n(-)-IMGCs (32%) or ly(-)-IMGCs (34%). Even in IMGCs, carcinoma cells may produce MMPs that can degrade the basement membrane, allowing them to permeate the lymph capillary. Ulcerations within the lesion may also facilitate the interchange of lymphatic flow between the mucosa and the submucosa, promoting the development of lymph node metastases.