The significance of anti-sialyl-Tn antibodies in patients with colorectal and breast cancer.

The sera of 54 individuals with colorectal or breast cancer, and 50 healthy volunteers were assayed for the presence of anti-bovine submaxillary mucin antibodies using an enzyme linked immunoassay. The serum levels of these antibodies were found to be significantly lower in people with breast (p < 0.001) or colorectal cancer (p < 0.001) with respect to healthy individuals. Within the colorectal cancer group the presence of antibodies was significantly lower in those individuals with poorly differentiated tumors compared to other histological grades (p < 0.05), but did not correlate with the presence of local or distant metastases or anatomical location of the tumor (p > 0.05). No correlation was found with respect to the age of the patient and the level of anti-sialyl-Tn antibodies (p > 0.05). Competition analysis with the anti-sialyl-Tn monoclonal antibody 3C2 indicated that the activity against bovine submaxillary mucin was primarily due to specificity for the sialyl-Tn epitope of the glycoprotein. In contrast to findings with other tumor associated antigens, we could find no evidence of an increase in the level of antibodies against this epitope.