KRT18 and breast cancer: Pretreatment levels of CK18–Asp396 in the sera of patients with primary breast cancer, (n=152), recurrent breast cancer (n=49) or normal controls (n=82) (Ueno et al, 2003), demonstrated that patients with primary cancer had higher serum CK18–Asp396 levels than the normal controls (P=0.0001) and that patients with recurrent cancer had higher serum CK18–Asp396 levels than both the primary breast cancer patients and the normal controls (median values 180.5 vs 165.7 vs 156.2 U l−1 (P<0.0001 and P=0.008, respectively)).