nos-trum. pronunciation: \nos'-trum\. noun. Etymology: Latin, neuter of noster our, ours.
1. a medicine of secret composition recommended by its preparer but usually without scientific proof of its effectiveness.
2. a usually questionable remedy or scheme.
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Wednesday, April 6, 2011

Estrogen Replacement And Reduced Risk Of Breast Cancer. The Caveats.

Lots of news today about a large study showing reduced risk of breast cancer in hormone replacement therapy (HRT).  But most articles don't list all the limitations in the study.

We've heard scary stories about the use of hormone replacement, based on research done over the last twenty years.  More specifically, higher risk of breast cancer, heart disease, and stroke.  Combined estrogen-progestin was the main offender, but all replacement has been thought to confer some risk.

Now comes a large scale, government study (NIH, not industry) from the Women's Health Initiative (WHI).  The WHI was started twenty years ago and has followed a number of women's issues.  You can see one example of the news reporting here (Assoc Press, Apr 5).

The study showed a 23% reduction in breast cancer for those women taking conjugated estrogen versus placebo.  And no increased risk for a range of other conditions.  Mean estrogen use was 5.9 years; follow up was 10.7 years.

Everybody is surprised, and a few are questioning the results.

But if they knew the narrow focus, and specific conditions of the study, there would be less discussion.  Here are some:

1.  The conjugated estrogen taken by the subjects was equine in origin.  This leaves open the question of whether synthetic estrogens, now used by many women, may impose more or less risk.
2.  Only the women who took estrogen after hysterectomy had the reduced risk.  Taking estrogen-only for the two-thirds of women over 50 who haven't had hysterectomy is thought to increase risk, so they are prescribed combination estrogen-progestin--also a risk but less so, and only when symptoms are severe.
3.  The study participants took the estrogen only until 2004--when risk was thought to accompany any use of hormone replacement--but were followed subsequently--not taking estrogen--until 2009.  That is, the treatment group had not taken estrogen for five years.  Many women take Ogen or other products well after menopause symptoms have resolved.  This study doesn't address post-symptomatic, continued therapy.
4.  Further, the reduced risk may be due to stopping the estrogen after symptoms resolve.  In other words, using estrogen in the peri-menopausal hysterectomy patient, and then subsequently terminating the therapy, may all be necessary elements of the reduced risk. 
5.  The age range included in the study was 50-79 years.  There's some data to suggest that women who began HRT before 50 or who take it in the late 70's are at increased risk.  The study can't answer this.
6.  After the estrogen-takers stopped the drug in 2004, the (low) increased risk of stroke found at that time fell to the level of risk of women who had not taken HRT.  So the risk went away when the drug did.  Again, this applies to estrogen from horses only.
7.  Lastly, the risks we're addressing here are relatively small to begin with.

If that isn't overwhelming enough, here's the data analysis for Onion Peelers,
"The intervention phase was a double-blind, placebo-controlled, randomized clinical trial of 0.625 mg/d of CEE compared with placebo in 10 739 US postmenopausal women aged 50 to 79 years with prior hysterectomy. [...] Over the entire follow-up, lower breast cancer incidence in the CEE group persisted and was 0.27% compared with 0.35% in the placebo group (HR, 0.77; 95% CI, 0.62-0.95)."

I've omitted a lot of the other risk data (hip fracture, etc) for simplicity.  Please see the study if you're interested.

The good news from this study is not that estrogen is safe; it's that we can see more clearly that risk differs depending on clinical history and the life stage at which hormones are acting.   This research makes distinctions about which patients need what, and at what time.

And takes women's health out of the "One Size Fits All" mode of thinking.

Doc D

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