Detection of estrogen receptor-beta mRNA in breast cancer using RT-PCR

The estrogen receptor (ER) is the most useful marker currently available fo r breast cancer being used both to predict response to therapy and assess p rognosis. Recently, a new form of the ER, known as ER-beta, was identified. In this preliminary study we show that ER-beta mRNA was expressed less fre quently in breast cancers than ER-alpha. ER-alpha but not ER-beta levels co rrelated with ER protein as determined by ELISA. We conclude that ER-beta i s expressed in approximately 50% of breast cancers but it does not appear t o be detected by a widely available ELISA.