The effect of endocrine therapy on the levels of oestrogen and progesterone receptor and transforming growth factor-β1 in metastatic human breast cancer: an immunocytochemical study

Abstract

The levels of oestrogen receptor (ER), progesterone receptor (PR) and transforming growth factor- β 1 (TGF- β 1) were measured by immunocytochemistry in 19 patients prior to and 1 month after the start of endocrine therapy (tamoxifen 10 patients; aromatase inhibition 9 patients). A complete or partial response was observed in 10 patients. The proportion of cells showing ER staining was higher in responding patients, but there was no change observed with endocrine therapy in either responding or non-responding patients. In contrast, cells staining for PR in responding patients were significantly reduced following therapy (59 ± 9% to 24 ± 9%: P < 0.05). There was no reduction in immunocytochemical PR in non-responding patients, although the numbers of these patients with initially positive PR levels was small. Stromal tissue adjacent to tumour cells stained with the antibody to TGF- β 1, with particularly intense staining at the periphery of tumour cell aggregates. There was no correlation between the degree of TGF- β 1 staining and ER or PR status, and no evidence of a change with endocrine therapy. It is concluded that neither tamoxifen nor aromatase inhibitors produce a change in the ER content or TGF- β 1 content of breast tumours as detected immunocytochemically, but PR levels are significantly reduced after therapy in responding patients.