Racial differences in oestrogen receptor and peroxidase status of human breast cancer tissue.

Cytoplasmic oestradiol receptors and peroxidase from 170 tumours from patients with breast cancer were assayed. The results were analysed in terms of racial groups and menopausal status. It was found that 68% of the receptor-positive tumours were peroxidase-positive, while 59% of the receptor-negative tumours were peroxidase-positive. When results were analysed in terms of racial groups 68% of tumours from White patients were peroxidase-positive and receptor-positive, while only 48% of receptor-negative tumours in this group were peroxidase-positive. This contrasts with the finding of 57% receptor-positive/peroxidase-positive tumours as opposed to 70% receptor-negative/peroxidase-positive tumours in Black patients.