[Gonadotropin-releasing hormone receptors in human breast cancer tissue].

Analogues of gonadotropin-releasing hormone (GnRH) are presently being investigated for the treatment of metastatic breast cancer. Although their effects are thought to be mediated via the suppression of gonadotropins and gonadal steroids, they could possibly also act directly on the tumour. The binding of a GnRH-agonist to membrane fractions of 97 primary human breast carcinomas was investigated. In 43 cases (44%) the presence of specific GnRH receptor binding sites (above 3 fmol/mg membrane protein) was shown. GnRH receptor content was 6.2 fmol/mg membrane protein in estradiol receptor (ER) positive tissues and in ER negative tissues 2.0 fmol/mg membrane protein (p less than 0.05). Progesterone receptor (PR) positive contained 5.2 fmol/mg protein and PR negative carcinoma contained 2.0 fmol/mg membrane protein. In postmenopausal women GnRH receptor concentration was 5.4 and 2.9 fmol/mg membrane protein, respectively, in ER positive and negative tissues (p less than 0.05) whereas 4.4 and 5.2 fmol/mg membrane protein, respectively, in PR positive and negative samples. Binding of GnRH was positive (above 3 fmol/mg protein) in 33% premenopausal and in 54% of postmenopausal cases. Further clinical studies with GnRH analogues will clarify the therapeutic value of GnRH receptor determination in breast cancer.