Enzyme immuno assay of the estrogen receptor in breast cancer biopsy samples. A comparison with isoelectric focusing.

Abstract

The estrogen receptor (ER) was measured by isoelectric focusing (IF) and enzyme immuno assay (EIA) in 127 breast cancer samples. When comparing the two techniques quantitatively, a very high correlation coefficient was obtained (rs = 0.98; p less than 0.001). ER recovery increased, however, by a mean factor of 2.5 when EIA was used instead of IF. This increase seemed to be influenced by the ER concentration level, being lower at higher levels. The difference between IF and EIA did not seem to be due to menopausal status. A possible field of application for EIA might be measurement of ER in samples from patients on tamoxifen therapy. In five out of nine such samples, a considerably higher measurable amount of ER was found with EIA than with IF. EIA was also found to be a simpler and less time-consuming method than IF. These advantages should, however, be weighed against the present higher costs.