Oestrogen and progesterone receptor content and the distribution of histological grade in breast cancer.

Histological grading of 160 primary infiltrating breast carcinomas showed that both oestrogen and progesterone receptor status are strongly related to grade, tumours that are receptor positive tending to be of lower grade than the receptor negative. The nuclear factors used in grading were those that determined this association. In addition the absence/presence of both receptors was reflected in the grade present, beyond the correlation expected on the basis of either receptor alone.