Expression of sialyl-Tn in breast cancer. Correlation with prognostic parameters.

To investigate the expression of a simple mucin-type carbohydrate antigen (Sialyl-Tn/STn) and its putative relationship with established or potentially useful clinico-pathologic prognostic parameters in breast cancer, we studied forty-six cases of invasive breast carcinoma in formalin-fixed, paraffin-embedded tissue sections. STn antigen was detected by the HB-STn antibody using an avidin-biotin-peroxidase method. The parameters studied were tumour size, histologic grade, nodal status, proliferative index (with MIB-1), ER expression, ploidy, c-erbB-2 and p53 expression. STn expression was observed in 18 cases (39%) of breast cancer. The expression of STn was associated with axillary node metastasis, ER negativity and c-erbB-2 expression. A tendency towards an association between STn immunoreactivity and high histologic grade was also found. No correlation was observed between STn immunoreactivity and age, tumour size, proliferative index, ploidy and p53 expression. We conclude that the detection of STn immunoreactivity may be useful for predicting the likelihood of lymph node metastasis and that the outcome of patients with breast cancer should be further investigated in order to find whether or not the data of the present study are confirmed in larger series.