Oestrogen receptor activity in intraduct and invasive breast carcinomas.

Breast cancers analysed for oestrogen receptor activity over a ten-year period have been surveyed in order to select a group of intraduct carcinomas without invasion and a second, control group of invasive carcinomas without intraduct carcinoma. Examination of histological sections taken from the face of the tumour samples used for receptor analysis showed only 13 purely intraduct carcinomas without any invasion. Each of these was matched for age, menstrual status, hospital of origin, and approximate assay date with two purely invasive ductal carcinomas of no specialized type (26 invasive carcinomas in all). In invasive carcinomas, a significantly higher proportion of the specimen was occupied by malignant cells (mean 30%) than in the intraduct carcinomas (mean 15%), and receptors were detected more frequently (77% versus 46%) and at higher concentrations (mean 26 times on a wet weight basis, 19 times on a protein basis). When allowance was made for the difference in cellularity between the groups, the invasive carcinomas still contained significantly higher concentrations of receptor protein (mean = ten times more on a wet weight basis). These findings suggest that the expression of the gene encoding the receptor protein tends to be a property either maintained, or acquired upon progression to invasive disease. Further studies will be needed to determine whether or not the established prognostic and predictive values of receptor measurements apply to non-invasive disease, and to clarify the relationship between receptor expression in benign and malignant breast in relation to morphological changes.