THE INFLUENCE OF PROGESTINS ON RECEPTOR LEVELS IN BREAST-CANCER METASTASIS

  • 1 January 1987
    • journal article
    • research article
    • Vol. 7  (1) , 119-124
Abstract
The influence of oral high-dose (HD) medroxyprogesterone acetate (MPA) and megestrol acetate (MA) treatment on steroid hormone receptor levels in metastatic breast tumor tissue was investigted. In ten postmenopausal women with advanced breast cancer,receptor biopsies were obtained from the same tumor before the start, and one and eight weeks after the start of oral HD progestin treatment. Endocrine treatment had been stopped in all patients at lest five weeks before the start of progestin treatment. Estradiol receptor (ER) levels were reduced by 26.9% and 20.0%, respectively after one and eight weeks of treatment. Progestrone receptors (PgR) were significantly reduced to undetectable levels, possibly due to MPA and MA binding to PgR.A stepwise decrease in androgen receptors (AR) was observed, indicating that the two progestins (MPA and MA) may also act through AR, and/or interfere with the replenishment of AR.