COMPARISON OF VARIANT EXPRESSION OF ESTROGEN-RECEPTOR MESSENGER-RNA IN NORMAL BREAST-TISSUE AND BREAST-CANCER

To investigate whether estrogen receptor abnormalities are associated with resistance of breast cancer to endocrine therapy, we compared est rogen receptor mRNA between normal breast tissue and carcinoma. Using the RT-PCR, paired cancer and normal breast tissue specimens from 15 p atients were analyzed. Exon-deleted variants were found in both tumor and normal tissue, with differences of variant expression between norm al and tumor tissue being observed. One patient showed multiple deleti ons in the hormone-binding domain. Alterations in the amount and/or ki nd of variant ER expression may be important in determining the respon se of breast cancer to endocrine therapy.