Cytosolic oestrogen receptor content of breast cancer tissue in blacks and whites.

We have examined the oestradiol receptor (ER) content of cytosols from 560 Black and White patients. The tumours from the White group contained a significantly lower proportion on ER-negative tumors (35.4%) compared with those from the Black group (46.5%). The proportion of ER-positive tumours is significantly greater in the post- than in th premenopausal White group. The frequencies of ER-positive tumours in the post- and premenopausal Black groups are not significantly different, resembling the situation described by others in Japanese women.