CDH17 is a Highly Specific and More Sensitive Marker Than CK20 and CDX2 in Colon Adenocarcinoma and in Stomach Adenocarcinoma

CDH17 stained 100% (99/99) of colon adenocarcinoma, whereas CK20 and CDX2 stained 92% (91/99) and 96% (95/99), respectively (Figure 1A-C and Figure 2A-C). In stomach adenocarcinoma, CDH17 stained 73% (50/69), CK20 28% (19/69) and CDX2 16% (11/69) (Figure 3A-C) (Table 1). CDH17 was positive in 35% (10/29) of pancreatic ductal cell adenocarcinomas (Figure 4A) (data not shown). All cases of pancreatic ductal adenocarcinoma cases that stained positive for CDH17 were low grade (1 and 2), except for one high-grade case that CDH17 and CK20 were both positive and CDX2 was negative (data not shown). One case of high-grade pancreatic adenocarcinoma (1/10) also stained for CDH17 and CK20. In a direct comparison, CK20 was positive in 13% (5/39) of pancreatic cancers and CDX2 was negative in all pancreatic cancers (Table 1). In ovarian cancers, including serous papillary, endometrioid and mucinous adenocarcinoma, CDH17 stained 11% (8/70), and CDX2 and CK20 stained 13% (9/70) and 14% (10/70), respectively. In mucinous adenocarcinoma, CDH17 and CK20 stained 80% (4/5) and CDX2 stained 60% (3/5) (Figure 4B). In lung cancers, CDH17 (M) stained 6% (4/71) and CDX2 and CK20 stained 1% and 3%, respectively. CDH17 stained 12% (4/33) lung adenocarcinomas; however, only low grade (1-2) lung adenocarcinomas stained with CDH17 (Figure 4C), as all other phenotypes of lung cancers were negative including lung squamous cell carcinoma, neuroendocrine carcinoma, large cell carcinoma and small cell carcinoma. CDH17 stained 2% (1/57) in liver cancer; however, HSA and Arginase-1 were negative in the same case. CDH17 was negative in all other cancers types tested (Table 1); and CDH17 was negative in all normal tissues except gastrointestinal epithelial cells (colon and small intestine) and in normal pancreatic ducts.