Carbohydrate antigen 72-4 (CA 72-4) is a high molecular glycoprotein antigen. A good correlation has been reported between CA 72-4 levels and tumor stage and size, and it is expressed at high levels in gastrointestinal tumors, pancreatic cancer, endometrial cancer, and ovarian cancer. CA 72-4 may serve as a marker of choice for treatment monitoring and follow-up care in patients with gastrointestinal cancers.