Serum and immunohistochemical studies of NCC-ST-439 in breast cancer.

It has been thought that NCC-ST-439 antigen (ST-439) is a tumor-related carbohydrate antigen. The authors conducted serum and immunohistochemical studies to investigate the clinical significance of ST-439 in breast cancer. The level of serum ST-439 was elevated in advanced and recurrent breast cancers. In comparison with CEA and CA15-3, ST-439 was superior in sensitivity but inferior in specificity to these markers. The level of serum ST-439 showed no correlation with the levels of CEA or CA15-3. In the combination assay of these three markers, 80.6% of recurrent cases and 33.8% of primary cases were positive. Immunohistochemically, the expression of ST-439 was observed in 28.1% of noncancerous mammary duct epithelium and in 38.1% of the cancerous portion. From the above, we concluded that ST-439 was a tumor-related antigen and could be a tumor marker with high sensitivity in breast cancer.