The cytochemical detection of oestrogen receptors in fine needle aspirates of breast cancer; correlation with biochemical assay and prediction of response to endocrine therapy.

A total of 98 breast aspirates from patients with breast cancer have been fixed and stained for oestrogen receptors using the Abbott ERICA kit. In a preliminary series of 41 aspirates, cytochemical staining index (% cells staining x mean intensity) related to the receptor concentration determined biochemically on a subsequent biopsy with a correlation coefficient of +0.65. In a second series of 56 aspirates examined after lysis and cytocentrifugation, the correlation coefficient was +0.73. For 14 patients, the response of the primary tumour to endocrine therapy was assessed objectively by serial clinical and mammographic measurements (Forrest et al., 1986) and was found to relate strongly to the cytochemical staining of the initial aspirate. The potential and limitations of this technique are discussed.