Reverse transcription-polymerase chain reaction (RT-PCR) assays of estrogen and progesterone receptors in breast cancer.

The biochemical assay for estrogen (ER) and progesterone receptors (PR) as a routine procedure in the clinical evaluation of human breast cancer is well established. Since there are various and complex phenotypic alterations in breast cancer, there is a need for a multiparametric assessment of the biological profile of breast tumours. However, multiparametric analysis requires a large amount of tissue and various methods of quantitative analysis involving expensive reagents. Thus, an evaluation of the diagnostic and prognostic applications of the measurement of mRNA expression by reverse transcription polymerase chain reaction (RT-PCR) has been initiated. A series of 105 surgical samples of breast cancer was assayed for ER and PR expression in parallel by semi-quantitative RT-PCR and standardized enzymoimmunoassays (EIA). 79 (75%) tumour samples were positive for ER expression by EIA, and 86 (82%) by RT-PCR. This shows a good concordance of the two methods (90%). In the case of PR expression 65 (62%) tumour samples were positive by EIA and only 53 (51%) samples by RT-PCR. In conclusion ER-RT-PCR appears to provide information concerning ER expression similar to ER-EIA, and may be an alternative to this assay. The information derived by PR-RT-PCR appears somewhat different from PR-EIA. We are currently evaluating the biological and clinical significance of this discrepancy.