COMPARISON OF A NEW MICROPLATE ESTROGEN-RECEPTOR (ER) ENZYME-IMMUNOASSAY WITH OTHER ER DETECTION METHODS

In a study involving 50 breast cancer tumours, we compared two oestrog en receptor (ER) detection methods developed by us - a microplate immu noenzymometric assay (EIA96) and an immunohistochemistry kit (HistoCIS -ER) - with the radioligand assay (RLA), the Abbott immunoenzymometric assay ER-EIA and the reverse transcriptase polymerase chain reaction technique (RT-PCR). Among the three ER protein cytosolic assays (EIA96 , ER-EIA and RLA), the two EIAs showed the best agreement (y = 1.086x - 7.840; r(2) = 0.876). At the calculated optimal cut-off values (8 an d 14 fmol mg(-1) protein for EIA96 and RLA respectively), EIA96 was mo re sensitive than RLA (0.94 for EIA96, 0.88 for RLA), but slightly les s specific (0.82 for EIA96, 0.94 for RLA). The Cox logistical regressi on model applied to EIA96, RLA and RT-PCR showed that EIA96 discrimina ted the best between ER-EIA(+) and ER-EIA(-) samples. The RT-PCR techn ique and HistoCIS-ER both had a positivity-negativity concordance of 8 6% with EIA96.