Cytochemical and competitive protein binding assays for estrogen receptor in breast disease. A comparative study of 62 cases.

Estrogen receptor content of breast lesions was estimated using a fluorescent cytochemical technique and a competitive protein binding assay. Of 48 cancers examined, an equal proportion contained significant quantities of receptor by either method (62.5%). The concordance between methods for individual patients was also 62.5%. A greater proportion (26%) of patients younger than 45 years of age had receptor-positive cancers using the cytochemical method than were found by the biochemical method (10%). Benign breast disease was also studied using the fluorescent cytochemical method. A greater proportion of lesions containing estrogen receptors was found compared with that cited in the literature for the competitive protein-binding assay. Because of the methodologic simplicity of the fluorescent cytochemical method, further study for routine use is indicated.