Serum sialyl transferase levels in patients with metastatic breast cancer treated by chemotherapy.

Serum sialyl transferase (SST) was measured in 49 female patients with advanced breast cancer and 60 female controls. The mean SST level was significantly raised in patients with advanced breast cancer. There was no correlation between specific sites, or numbers of sites of metastatic disease and SST levels. The patients with advanced breast cancer were all treated with chemotherapy; in 13/21 responders there was a significant fall in SST and in 2 responders a significant rise in SST. The 6 patients who died after one course of chemotherapy had a significantly higher mean SST than those surviving longer. SST appears to lack sufficient specificity to be of practical value as a marker of response in patients with breast cancer treated by chemotherapy, though constant measurement of changes in SST may be of use in monitoring drug response. Raised SST at the commencement of chemotherapy may signify poor prognosis.