Breast cancer risk and HRT – what matters most?

Posted by on Jan 26, 2009 in HRT | 3 comments

Data from the San Antonio Breast Cancer Symposium last month provided definitive evidence that HRT increases the risk of breast cancer by 26% in menopausal women.  However, does route of administration (e.g., patch, oral) or type of  HRT matter?

According to a study in the journal Breast Cancer Research and Treatment, route of administration does not matter. But the progestagen component does.

Data were extrapolated from 80,377 postmenopausal women living in France and participating in E3N (a study designed to investigate risk factors for cancer) between 1990 and 2002.  At the study’s start, the average age of participants was 53 years. HRT types included estrogen only and estrogen plus progesterone, dydrogesterone combinations or other types of progesterone.

Over the study period 2,354 cases of invasive breast cancer occurred. Compared with women who never used HRT, women using estrogen alone had a 1.29-fold increased risk of developing breast cancer. However, breast cancer risk varied significantly depending upon the type of progestagen:

  • Risk was significantly lower with estrogen-progestagen HRTS containing progesterone or dehydrogesterone than with estrogen combinations involving other types (e.g., nomegestrol acetate, norethisterone acetate, medroxyprogesterone acetate)
  • The aformentioned combinations Ii.e. estrogen plus progesterone or  dehydrogesterone)  were associated with no or only a slight increase in breast cancer risk (1 fold greater or 1.16 fold greater, respectively).
  • The results remained the same when analysis was restricted women whose age at the start of menopause could be most accurately determined.

Although the effect of progestagen remains somewhat unclear, and factors such as experimental conditions, length of time taking them and dose can influence results, the researchers did conclude that some HRT combinations may be safer than others.

Researchers also emphasize that further study is needed, and that medical experts are still unsure how HRT combinations affect other disease risks, such as heart disease, stroke and colorectal cancer.

Meanwhile, if you are taking HRT, talk to your health practitioner and find out which progestagen you’re taking. Better safe than sorry, right?!


  1. 1-30-2009

    Good post, as usual, Liz.

    I just started taking HT in December 2008. I am taking what is considered bio-identical hormones, that is, estradiol (Estrogel) and a progesterone pill (Prometrium).

    After much thought and research, I finally decided to give HT a short term trial to get over the hump of this transition (due to severe sleep deprivation, due only in part to night sweats).

    So far so good. I’m sleeping well, and hope to improve my health and QOL. My plan is to only stay on HT for 6 months to a year, and I’m being followed by my doctor regularly.

    Did you see any of Oprah’s latest shows? I never watch her, but I heard she has done a couple of shows on hormones and menopause. Now that Oprah has “discovered” that she is perimenopausal, we may finally get some much-needed action on the peri- and post-menopausal front!

    Cheers, Emily

  2. 1-30-2009

    Thanks Emily! Glad it was helpful. I’ve heard a bit about Oprah and her journey but unfortunately haven’t caught any of the shows in real time yet. I’ll need to get my act together and see if I can find them on YouTube.

    Glad that the HT is working for ya!

  3. 2-1-2009

    Hmmm… I just tried finding the clips on youtube, but couldn’t come up with them. Maybe they are on the site? They were talking about bioidenticals, not HT (though it was pretty confusing because they didn’t do a good job distinguishing the two). Here’s a link to a bioidenticals article: Bioidenticals come center stage.


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