AIM:To assess subcellular localization of KL-6 mucinand its clinicopathological significance in colorectalcarcinoma as well as metastatic lymph node and livertissues.METHODS:Colorectal carcinoma tissues as wellas metastatic lymph node and liver tissues werecollected from 82 patients who underwent colorectomyor hepatectomy.Tissues were subjected toimmunohistochemical analysis using KL-6 antibody.RESULTS:Of the 82 colorectal carcinoma patients,6showed no staining,29 showed positive staining only inthe apical membrane,and 47 showed positive stainingin the circumferential membrane and/or cytoplasm.Positive staining was not observed in non-cancerouscolorectal epithelial cells surrounding the tumor tissues.The five-year survival rate was significantly lower incases showing positive staining in the circumferentialmembrane and/or cytoplasm (63.0%) than thoseshowing positive staining only in the apical membrane(85.7%) and those showing no staining (100%).Statistical analysis between clinicopathological factorsand subcellular localization of KL-6 mucin showed thatKL-6 localization in the circumferential membrane and/or cytoplasm was significantly associated with the presenceof venous invasion (P=0.0003),lymphatic invasion(P<0.0001),lymph node metastasis(P<0.0001),liver metastasis (P=0.058),and advanced histologicalstage(P<0.0001).Positive staining was observed inall metastatic lesions tested as well as in the primarycolorectal carcinoma tissues.CONCLUSION:The subcellular staining pattern ofKL-6 in colorectal adenocarcinoma may be an importantindicator for unfavorable behaviors such as lymph nodeand liver metastasis,as well as for the prognosis ofpatients. AIM: To assess subcellular localization of KL-6 mucinand its clinicopathological significance in colorectalcarcinoma as well as metastatic lymph node and livertissues. METHODS: Colorectal carcinoma tissues as wellas metastatic lymph node and liver tissues werecollected from 82 patients who underwent colorectomyor hepatectomy.Tissues were Toimmunohistochemical analysis using KL-6 antibody .RESULTS: Of the 82 colorectal carcinoma patients, 6 shedded no staining, 29 showed positive staining in inthe apical membrane, and 47 showed positive staining in the circumferential membrane and / or cytoplasm. -cancerouscolorectal epithelial cells surrounding the tumor tissues. the five-year survival rate was significantly lower incases showing positive staining in the circumferential sheet and / or cytoplasm (63.0%) than thoseshowing positive staining only in the apical membrane (85.7%) and those showing no staining (100%). Statistical analysis between clinicopath The biological factors and subcellular localization of KLKL-6 localization in the circumferential membrane and / or cytoplasm were significantly associated with the presenceof venous invasion (P = 0.0003), lymphatic invasion (P <0.0001), lymph node metastasis (P < 0.0001), liver metastasis (P = 0.058), and advanced histologicalstage (P <0.0001) .Positive staining was observed in all metastatic lesions tested as well as in the primarycolorectal carcinoma tissues. CONCLUSION: The subcellular staining pattern of KL-6 in colorectal adenocarcinoma may be an importantindicator for unfavorable behaviors such as lymph node and liver metastasis, as well as for the prognosis of patients.