结直肠癌是全球一项重要的致残和致死原因。尽管在原发部位对结直肠癌的诊断是直截了当的，但在未知原发肿瘤的转移瘤中，它可能代表一个诊断问题。因此，免疫组织化学分析与形态学评估和临床数据的相关性结合起来变得至关重要，因为明确转移的原发部位很重要，因为某些特定的肿瘤类型可能对靶向分子治疗有良好的反应。因此，确立可靠的诊断标志物以确认或排除结直肠来源是必需的。研究cadherin 17和CDX2在结直肠癌中的表达，并评估它们在识别未知原发部位的转移性结肠和非结肠腺癌的诊断作用。本次回顾性研究包括65例腺癌病例：35例结直肠腺癌（原发或转移）和30例非结直肠腺癌。它们来源于2010年至2015年间埃因沙姆大学和埃因沙姆大学专科医院病理科档案。使用cadherin 17和CDX2抗体进行免疫组织化学研究。在检测结肠腺癌方面，CDX2和cadherin 17的敏感性和特异性分别为97.1%和53.3%以及100%和50%。相对应的，CDX2与cadherin 17的阳性预测值（PPV），阴性预测值（NPV）和总体准确率分别为70.8%、94.1%和76.9%以及70%、100%和76.9%。当疑似结直肠癌时，cadherin 17是一种更敏感的标志物，可用于诊断原发部位不明的癌症。©2020年，施普林格科学与商业媒体有限责任公司，施普林格自然集团的一部分。

Colorectal cancer is a major cause of morbidity and mortality throughout the world. Although the diagnosis of colorectal cancer is straightforward in primary site, yet it may represent a diagnostic problem in metastatic tumor of unknown primary origin. Hence, immunohistochemical analysis in combination with morphologic assessment and correlation with clinical data becomes crucial, because it is important to specify the primary site of metastasis since some specific tumor types may respond well to targeted molecular therapies. Therefore, establishment of reliable diagnostic markers that confirm or rule out colorectal origin is mandatory.To study the expression of cadherin 17 and CDX2 in colorectal carcinoma and to evaluate their diagnostic roles in identifying metastatic colonic from non-colonic adenocarcinomas in cancer of unknown primary site.This retrospective study included 65 cases of adenocarcinomas: 35 cases of colorectal adenocarcinoma (primary or metastatic) and 30 cases of non-colorectal adenocarcinoma. They were retrieved from the archives of Pathology Department of Ain Shams University and Ain Shams University Specialized Hospitals during the period from 2010 to 2015. Immunohistochemical study was performed using cadherin 17 and CDX2 antibodies.The sensitivity and specificity of CDX2 and cadherin 17 are 97.1% and 53.3% and 100% and 50% in detecting colonic adenocarcinoma respectively. The PPV, NPV, and overall accuracy of CDX2 versus cadherin 17 were 70.8%, 94.1%, and 76.9% versus 70%, 100%, and 76.9% respectively.Cadherin 17 is a more sensitive marker than CDX2 in diagnosis of carcinoma of unknown primary site especially when colorectal carcinoma is suspected.© 2020. Springer Science+Business Media, LLC, part of Springer Nature.