KRT18 and esophageal cancer: For the 15 esophageal cancer patients, the overall CTC positivity was 87% (13/15, non-color column) with a range of 2–34 CTCs/7.5 ml blood; 9 of them were CK18-/iFISH+ patients (9/13, 69%, black), and the remaining 4 were CK18+/iFISH+ patients (4/13, 31%, grey).