Synthetic Estrogen & Progestin Increase Cancer

A recent robust study published October 20th, 2010 in The Journal of the American Medical Association concluded, “Estrogen plus progestin was associated with greater breast cancer incidence, and the cancers are more commonly node-positive.  Breast cancer mortality also appears to be increased with combined use of estrogen plus progestin.”  What does this mean for women wanting to take Hormone Replacement Therapy (HRT) after menopause?  What does the study actually mean?  Are hormones safe?  What type of hormones were they actually studying?  Are there alternatives?  Read on…

This particular study (abstract available at: has already made huge headlines.  Here is a sample from an email article from the Endocrine Society.  This is the largest endocrinological association in the world of which I am a proud member:

The CBS Evening News (10/19, story 4, 2:35, Couric) reported, “For women going through menopause, the decision about whether to take hormone replacement therapy has been controversial and confusing.” In 2009, “40 million prescriptions for hormones were filled here in the US, but there’s new evidence tonight that this treatment may be even riskier than previously thought.”
ABC World News (10/19, story 4, 0:25, Sawyer) reported, “The Women’s Health Initiative reports today that among post-menopausal women, the use of estrogen and progestin is not only linked to an increased risk of breast cancer, but the kind that kind of cancers that have higher fatality rates. The safety of more hormone replacement therapy was first questioned in 2002.”
        NBC Nightly News (10/19, lead story, 2:30, Williams) reported, “Our lead story tonight has to do with an emotional and perplexing topic for millions of American women — hormone replacement therapy; specifically, its relationship to breast cancer.” Chief science reporter Robert Bazell explained that a new study published Oct. 20 in the Journal of the American Medical Association “suggests that hormone replacement therapy, estrogen plus progestin, once the most commonly prescribed medication for women 50 and older, not only increases the risk of aggressive breast cancer, but increases the risk that cancers will be more advanced and deadly.”
                On its front page, the New York Times (10/20, A1, Grady) reports, “Hormone treatment after menopause, already known to increase the risk of breast cancer, also makes it more likely that the cancer will be advanced and deadly,” the study found. Specifically, “women who took hormones and developed breast cancer were more likely to have cancerous lymph nodes, a sign of more advanced disease, and were more likely to die from the disease than were breast cancer patients who had never taken hormones.” Notably, “the treatment studied was the most commonly prescribed hormone replacement pill, Prempro [conjugated estrogens and medroxyprogesterone], which contains estrogens from horse urine and a synthetic relative of the hormone progesterone.”

It is  this last line that is the most poignant and telling.  Just as in the Women’s Health Initiative study (WHI) from 2002, they were studying Premarin (synthetic conjugated estrogen from horse urine), Provera (synthetic progesterone, ie “progestin”), and the combination product Prempro that contains both Premarin and Provera.  After the WHI was abruptly halted from the negative study results, we heard the first of synthetic hormone replacement therapy leading to an increased risk for breast and uterine cancer in women.  This newly published study in JAMA, with over 16,000 women studied since 2005, also showed a significant increase in the incidence and the agressiveness of breast cancer in women.

This is simply no surprise.  We have known and been suspicious that “synthetic” hormone replacement therapy has inherent increased risks for breast cancer for years.

The problem that exists now is the continual propagated fear that ALL estrogen and progesterone replacement therapy is unsafe.  But, again, the recent study, as well as the WHI from 2002, were both studying synthetic HRT.  The important concept to understand is that “not all hormones are created equally.”

Fortunately, menopausal women have a choice.

Bio-equivalent (aka bioidentical) hormone replacement therapy offers an excellent effective and SAFE alternative for women seeking relief from the symptoms and conditions related to menopause.  Remember, there are answers out there for you.  Seek the advice of a trained healthcare provider to help you make the most informed and safe decision for you.

For more information on the safety of natural bioequivalent hormone replacement therapy, be sure to keep up with this blog.  I have been working with natural bioidentical hormone replacement therapy since 2006, treating thousands of post menopausal women, and have not witnessed an increase in the incidence of breast cancer with my patients.

For more technical information, see “The Bioidentical Hormone Debate: Are Bioidentical Hormones (Estradiol, Estriol, and Progesterone) Safer or More Efficacious than Commonly Used Synthetic Versions in Hormone Replacement Therapy?”  By Kent Holtorf, MD.  Published in © Postgraduate Medicine, Volume 121, Issue 1, January 2009.  Find the abstract here, at

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