Histochemically demonstrable enzyme activities and their independence of the hormone receptor content in female breast carcinoma

Acid phosphatase, leucine aminopeptidase, monoamine oxidase and non specific esterase activities were histochemically demonstrated in specimens derived from 15 infiltrating ductal carcinomas of female breast. The relative areas occupied by the enzyme‐positive carcinoma cells were visually estimated and, in the cases of leucine aminopeptidase, assessed morphometrically. All enzyme activities were found to be subject to major variations within a single carcinoma and between individual carcinomas, and the activity of any single enzyme was independent of that of three others. None of the enzyme activities correlated with the estrogen and progesterone receptor values, nor the histological grade of malignancy of the tumour. Thus, histochemically demonstrable enzyme activities seem to be of no use in predicting the hormone receptor content in infiltrating ductal carcinomas of the female breast.