Medroxyprogesterone acetate breasts

Low-dose hormone therapy (conjugated equine estrogen 0.45 mg and medroxyprogesterone acetate 1.5 mg/day) has demonstrated equivalent symptom relief and bone density preservation without an increase in endometrial hyperplasia. Whether such lower doses will be safer (cause less venous thromboembolism and breast cancer) remains to be seen. 

Li S, Levesque C, Geng CS, Yan X, Labrie F (1995) Inhibitory effects of medroxyprogesterone acetate (MPA) and the pure antiestrogen EM-219 on estrone (El)-stimulated growth of dimethylbenz(a)anthracene (DMBA)-induced mammary carcinoma in the rat. Breast Cancer Res Treat 34 147-159... 

Progesterone is synthesized in the corpus luteum in a cycle timed to the menstrual cycle. Synthesis continues should pregnancy develop. Progestins such as megestrol acetate and medroxyprogesterone acetate find use in therapy for metastatic breast cancer. 

Progestins, steroid compounds similar to progesterone, such as hydroxyprogesterone caproate (28.3.6), medroxyprogesterone acetate (28.3.7), and megestrol acetate (28.3.7), are used for palliative treatment of breast carcinomas and renal tumors. Progestins can have a direct local effect on cells, and can simultaneously lower the quantity of leutenizing hormone. 

Estrogens with or without progestins should not be used for the prevention of cardiovascular disease. The Women s Health Initiative (WHI) study reported increased risks of myocardial infarction, stroke, invasive breast cancer, pulmonary emboli, and deep vein thrombosis in postmenopausal women (50 to 19 years of age) during 5 years of treatment with oral conjugated estrogens (0.625 mg) combined with medroxyprogesterone acetate (2.5 mg) relative to placebo.62... 

Many studies have shown that lactation is not adversely affected by depot medroxyprogesterone acetate and that breast-milk production may even be increased (35). Because of the low binding affinity of medroxyprogesterone to sex hormone binding globulin, the concentration of steroids in the milk is close to that in the maternal plasma, unlike the 19-nortestosterone derivatives. 

Depot medroxyprogesterone acetate should not be used in women with breast cancer, genital cancer, undiagnosed uterine bleeding, or suspected pregnancy (37), but these are merely logical precautions. 

Wander HE, Nagel GA, Blossey HC, Kleeberg U. Aminoglutethimide and medroxyprogesterone acetate in the treatment of patients with advanced breast cancer. A phase II study of the Association of Medical Oncology of the German Cancer Society (AIO). Cancer 1986 58(9) 1985-9. 

Skegg DC, Noonan EA, Paul C, Spears GF, Meirik O, Thomas DB. Depot medroxyprogesterone acetate and breast cancer. A pooled analysis of the World Health Organization and New Zealand studies. JAMA 1995 273(10) 799-804. 

Medroxyprogesterone acetate and its metabolites are excreted in breast milk, so women who breastfeed should wait until 6 weeks post partum before starting Depo-Provera, when the infant s enzyme system should be more mature. Norethisterone enantate 200 mg (Noristerat) is shorter acting than Depo-Provera, 8 weeks, and is used to provide contraception after administration of the rubella vaccine, and until a partner s vasectomy has taken effect. It can also be used in the longer-term but only on a named patient basis. 

Reports on adverse reactions to lower doses of medroxyprogesterone acetate are not entirely consistent, probably because of differences in pharmaceutical formulation which markedly affect the drug s systemic availability. However, high doses of medroxyprogesterone acetate are extensively used for the treatment of hormone-depen-dent carcinomas (notably of the breast) and marked adverse effects occur consistently under these conditions (SEDA-12, 343). Such doses are likely to bring out the... 

World Health Organization Collaborative Study of Neoplasia and Steroid Contraceptives. Breast cancer and depo-medroxyprogesterone acetate A multinational study. Lancet 1991 44 419 30. 

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