The cytochemical demonstration of oestrogen receptors in human breast carcinomas

A cytochemical method has been used to demonstrate oestrogen receptor in histological sections of breast carcinomas, and has given similar qualitative results to the biochemical dextra-coated charcoal method. Two conjugation techniques were employed to couple horseradish peroxidase to 17 beta-oestradiol-6-O-carboxymethyloxime-bovine serum albumin. The periodate conjugation method led to a greater degree of coupling but a higher concentration was required for demonstration of oestrogen receptor than that needed when the two-stage glutaraldehyde conjugation method was use, even though this resulted in a lesser degree of coupling. Care in the preparation of tissue has been found to be essential. Formalin-fixed, paraffin-embedded tissue was unsuitable; rapid freezing of fresh tissue, only brief air-drying or acetone fixation of tissue sections and short-term storage were important. A correlation has been shown between the presence of oestrogen receptor in breast carcinomas and good histological differentiation. The poorer differentiated tumours were also found to contain fewer reactive cells.