KRT7 and cholangiocarcinoma: According to Chiu et al., CK7-positive/CK20-negative staining was seen in 9 out of 12 (75%) cholangiocarcinomas, but in none of the 25 colorectal cancer metastases examined, whereas CK7-negative/CK20-positive staining was seen in 1 out of 12 (8%) cholangiocarcinomas, and in 20 out of 25 (80%) colorectal cancer metastases [8].