Absence of association between oestrogen-receptor content and in vitro oestrogen sensitivity in human breast cancer.

Breast-cancer tissue from 25 consecutive patients was investigated for oestrogen receptor content and for oestrogen-induced changes in tritiated thymidine uptake by explanted cells. A higher oestrogen receptor content was not associated with any statistically significant increase in oestrogen sensitivity. Neither the dissociation constant (Kd values), nor the oestrogen binding capacity (f mol oestrogen bound/mg supernatant protein) was found to be associated with in vitro oestrogen sensitivity. One receptor-negative tumour showed oestrogen sensitivity in vitro.