Clinical significance of subcellular localization of KL-6 mucin in primary colorectal adenocarcinoma and metastatic tissues

AIM： To assess subcellular localization of KL-6 mucin and its clinicopathological significance in colorectal carcinoma as well as metastatic lymph node and liver tissues. METHODS： Colorectal carcinoma tissues as well as metastatic lymph node and liver tissues were collected from 82 patients who underwent colorectomy or hepatectomy. Tissues were subjected to immunohistochemical analysis using KL-6 antibody. RESULTS： Of the 82 colorectal carcinoma patients, 6 showed no staining, 29 showed positive staining only in the apical membrane, and 47 showed positive staining in the circumferential membrane and/or cytoplasm. Positive staining was not observed in non-cancerous colorectal epithelial cells surrounding the tumor tissues. The five-year survival rate was significantly lower in cases showing positive staining in the circumferential membrane and/or cytoplasm （63.0%） than those showing positive staining only in the apical membrane （85.7%） and those showing no staining （100%）. Statistical analysis between clinicopathological factors and subcellular localization of KL-6 mucin showed that KL-6 localization in the circumferential membrane and/or cytoplasm was significantly associated with the presence of venous invasion （P = 0.0003）, lymphatic invasion （P 〈 0.0001）, lymph node metastasis （P〈0.0001）, liver metastasis （P = 0.058）, and advanced histological stage （P〈 0.0001）. Positive staining was observed in all metastatic lesions tested as well as in the primary colorectal carcinoma tissues. CONCLUSION： The subcellular staining pattern of KL-6 in colorectal adenocarcinoma may be an important indicator for unfavorable behaviors such as lymph node and liver metastasis, as well as for the prognosis of patients.