Fluoresceinated estrone binding by cells from human breast cancers obtained by needle aspiration

Despite widespread use there are disadvantages associated with biochemical methods for ER determination. Since there is increasing emphasis on earlier detection of primary breast cancers there is clearly a need for a method which requires only small numbers of tumor cells. A variety of other clinical situations exist in which the availability of a technic that could supply information regarding tumor ER from a small cell population would be helpful. This report presents our experience with 17-fluoresceinated estrone (17-FE) binding for detecting the proportion of estrone binding cells in samples obtained by fine-needle aspiration of tumors prior to their removal. The findings from the aspirated cells employing 17-FE were compared with results obtained from aliquots of the same tumors following their removal using both cytochemical (17-FE) and biochemical (3H-estradiol binding) methods for ER determination. When biochemically determined ER values (fmol/mg cytosol protein) were compared to the proportion of fluorescent cells observed either in cells from needle aspirates prior to tumor removal or in cells from the removed tumor there was no direct quantitative relationship. That lack of correlation is to be expected and does not indicate that one or the other method is inappropriate. It was found, however, that 100% of tumors having ER levels greater than or equal to 10 fmol had greater than or equal to 10% marker positive cells. Fifty-four percent of tumors with a negative or borderline (less than 10 fmol) ER level had less than 10% marker positive cells. The less satisfactory correlation in biochemically ER negative tumors may be related to false negative biochemical determinations. The better correlation between results from the biochemical method and those with 17-FE binding using needle aspirates than between the former and the latter when cells from fragments of removed tumor were used for cytochemical analysis, and the lack of concordance in 17-FE binding by the two cell suspensions (from needle aspirates and from parts of the removed tumor) may be related to the heterogeneity of the cellular composition of a tumor as regards ER content and consequently to the methods of sampling. The authors' experience in this and previous studies using 17-FE for determination of the proportion of putatively ER positive cells indicate that the method is worthy of further evaluation and consideration for experimental and clinical use.