Quantitative analysis of heterogeneity of estrogen binding in human breast tumor specimens

A quantitative assessment was made of the heterogeneity of estrogen binding among histologically distinct regions and among nuclei within histologically uniform regions in ten human breast tumors. An autoradiographic method was used that employed sections from fixed tissues and required exposure times of one to two weeks. Grain counting of autoradiograms probably indicated both type I and type II estrogen binding. There were significant decreases in estrogen binding in all specimens after competition with excess diethylstilbestrol, suggesting that a component of binding was specific for estrogen. Significant differences in amount and distribution (nuclear vs cytoplasmic) of estrogen binding were seen not only among tissues with different histologies but also within histologically identical regions of a tissue. In histologically uniform regions, wide ranges of values for nuclear estrogen binding were seen. This method allows for the rapid evaluation of estrogen-binding profiles of tumor specimens and has potential for analyzing the process of neoplastic transformation in mammary epithelia as it affects, or is affected by estrogen binding.