THE EFFECT OF ENDOCRINE THERAPY ON THE LEVELS OF ESTROGEN AND PROGESTERONE-RECEPTOR AND TRANSFORMING GROWTH-FACTOR-BETA-1 IN METASTATIC HUMAN BREAST-CANCER - AN IMMUNOCYTOCHEMICAL STUDY

The levels of oestrogen receptor (ER), progesterone receptor (PR) and transforming growth factor-beta(1) (TGF-beta(1)) were measured by immu nocytochemistry in 19 patients prior to and 1 month after the start of endocrine therapy (tamoxifen 10 patients; aromatase inhibition 9 pati ents). A complete or partial response was observed in 10 patients. The proportion of cells showing ER staining was higher in responding pati ents, but there was no change observed with endocrine therapy in eithe r responding or non-responding patients. In contrast, cells staining f or PR in responding patients were significantly reduced following ther apy (59 +/- 9% to 24 +/- 9%: P < 0.05). There was no reduction in immu nocytochemical PR in non-responding patients, although the numbers of these patients with initially positive PR levels was small. Stromal ti ssue adjacent to tumour cells stained with the antibody to TGF-beta(1) , with particularly intense staining at the periphery of tumour cell a ggregates. There was no correlation between the degree of TGF-beta(1) staining and ER or PR status, and no evidence of a change with endocri ne therapy. It is concluded that neither tamoxifen nor aromatase inhib itors produce a change in the ER content or TGF-beta(1) content of bre ast tumours as detected immunocytochemically, but PR levels are signif icantly reduced after therapy in responding patients.