Sequential galactosyltransferase and carcinoembryonic antigen levels in advanced breast carcinoma

UDP-galactosyltransferase (GT), an enzyme that functions in the biosynthesis of glycoproteins, has recently been found to be a sensitive biologic tumor marker. In the present study, sequential GT levels were compared to simultaneous CEA determinations to establish which biomarker more accurately reflects changes in tumor activity in patients receiving therapy for advanced breast carcinoma. Serum levels of GT and CEA were measured each month in 38 patients undergoing combination chemotherapy for metastatic breast carcinoma. The results were correlated with the objective responses observed to chemotherapy during this period. Prior to the institution of chemotherapy, significant serum GT elevations were observed in 84.2% ($\text{32}\text{38}$) of the patients, while 55.3% ($\text{21}\text{38}$) had elevations in levels of CEA. During therapy 71.4% ($\text{10}\text{14}$) and 50% ($\text{7}\text{14}$) of the GT and CEA levels, respectively, decreased in patients who had an objective response to therapy. In the patients whose disease progressed on therapy, 75% ($\text{18}\text{24}$) had significant increases in GT levels during this interval, while 41.6% ($\text{10}\text{24}$) had increases in CEA (P < 0.01). Furthermore, in 11 patients (29.5%) serum GT alterations correctly reflected changes in tumor activity, while CEA levels remain static. These data indicate that GT is more sensitive than CEA as a marker for breast carcinoma and suggest that GT may be clinically useful in the management of patients with metastatic breast disease.