Ask The Expert Progesterone and Breast Cancer | Progesterone and Breast Cancer |
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There is much confusion surrounding progestins and breast cancer. The main cause of this confusion is that progestin, progesterone and medroxyrogesterone are deemed equivalent. They are not. They have a variety of different effects on different tissue. Sometimes, the effects are the opposite. In pharmacology this is quite normal with synthetic hormones having different and opposite effect on targets compared to the human hormone. This is particularly so since studies have shown an increase risk of breast cancer with medroxyprogesterone�a synthetic progestin. However, human identical progesterone has been demonstrated to have a protective effect on breast tissue.
Progesterone protects, synthetic progestins worsen risk in breast CancerThe risk of breast cancer was significantly greater (p<0.001) with HRT containing synthetic progestins that with HRT containing micronized progesterone, the RR being 1.4 and 0.9 respectively. There was 10% decrease in risk with bio-identical progesterone. Fouriner A et al, Breast cancer risk in relation to different types of hormone replacement therapy in the E3N-EPIC cohort Int J Cancer 2005 apr 10:114(3):448-54
Progesterone causes breast cells to differentiate (become normal) progesterone inhibits cell proliferationFoidert,J.M., Colin et al 1998 Estradiol and Progesterone regulate the proliferation of human breast epithelial cells, Ferility and Sterility may: 69(5):963-69 Malet,C et al 2000. Progesterone effect on cell growth,ultrastructural aspect and estradiol receptors of normal human breast epithelial (HBE) cells in culture. Journal of steroid Biochemistry and Molecular Biology, vol. 73 issue �, 171-181
Transdermal Progesterone inhibits cell proliferation in vivo while estradiol increase cell proliferation in vivo.In women with benign tumours estradiol increase proliferation by 230% while transdermal progesterone inhibited proliferation by 400% Chang,K.J. et al 1995. Influences of percutaneous administration of estradiol and progesterone on human breast epithelial cycle in vivo, Fertility and Sterility 63:785-791
Progesterone has cancer protective effects20 year prospective study from Johns Hopkins demonstrated that women with low progesterone had a 5.4 greater risk of breast cancer than women with normal levels of progesterone. Progesterone seemed to have a dramatic (10 fold) protective effect on other cancers as well. Cowan,L.D., L.Gordis, J.A. Tonascia, G.S. Jones 1981. Breast cancer incidence in women with a history of progesterone Deficiency. American Journal of Epidemiology 114: 209-17 For more information, email us at : This e-mail address is being protected from spam bots, you need JavaScript enabled to view it
For Further Reading"What your Doctor will not tell you about breast Cancer" by John r. Lee Warner books Share this link with your friends!              |