The use of CA15.3 as a serum tumour marker in breast carcinoma.

There is, as yet, no tumour marker which is sufficiently specific and sensitive for use in the routine assessment of breast cancer patients. CA15.3 is a recently described tumour marker determined by two monoclonal antibodies. We have estimated CA15.3 by immunoradiometric assay in 187 patients attending a breast clinic. Eighty-one patients with benign disease were used as controls and 32 U/ml was taken as the upper limit of the normal range (means + 3SD = 31.7). Of 58 women with Stage I and II disease, only four had abnormal concentrations of CA15.3 and all are disease-free at a mean follow-up of 31 months. Seven women with normal CA15.3 concentrations developed recurrent disease at a mean of 18.7 months (range 10-25 months). Seven-day postoperative values were significantly lower than pre-operative values. There was no association between the CA15.3 value and the axillary nodal status. The patients with disseminated disease had a wide range of CA15.3 concentrations and there was no association between the CA15.3 concentration and the apparent tumour load.