CEACAM5 and cancer: Tumor markers carcinoembryonic antigen (CEA), cancer antigen 27-29 (CA 27-29), and cancer antigen, breast 15-3 (CA 15-3) were monitored and remained within or near reference limits, with CEA less than 3.0 ng/mL, CA 27-29 less than 39.0 U/mL, and CA 15-3 less than 31 U/mL (see Table 1).