HRT could increase breast cancer risk

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Roman Bystrianyk - 26 Feb 2008 12:02 GMT

Kate Devlin Medical Correspondent, "HRT could increase breast cancer
risk", Telegraph, February 26, 2008,
Link: http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2008/02/26/nhrt126.xml

Hormone replacement therapy could increase the risk of developing
early signs of breast cancer after only one year, a study shows.

Previous studies have shown a link between HRT, which is taken by
millions to combat the effects of the menopause, and developing cancer
but suggested it was safe as long as it was taken for less than five
years.

In one of the largest studies of its kind, researchers looked at more
than 16,000 post-menopausal women, half of whom were given combined
HRT, which includes oestrogen and progestin, while the other half took
a placebo.

Within one year the group taking the hormones had a four per cent
greater risk of having an abnormal mammogram, or breast X-ray, than
those taking the placebo.

Over the five years of the study that figure rose to 11 per cent.

Similarly, the women taking HRT were at almost double the risk of
their doctor recommending a biopsy.

The study found that HRT compromised the ability of mammograms and
breast biopsies to diagnose breast cancer.

Researchers believe the increase in breast density caused by combined
hormones could be to blame.

During the study, 199 women in the HRT group and 150 women in the
placebo group developed breast cancer.

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ed@math.uchicago.edu - 28 Feb 2008 13:06 GMT

> Kate Devlin Medical Correspondent, "HRT could increase breast cancer
> risk", Telegraph, February 26, 2008,
> Link:http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2008/02/26/nhrt1...
>
> Hormone replacement therapy could increase the risk of developing
> early signs of breast cancer after only one year, a study shows.

Roman,

This result is not at all surprising. The recent WHI study showed
that the synthetic progestin medroxyprogesterone acetate (MPA)
definitely increases the risk of developing breast cancer (BC) and
increases the growth rate fof the observed BC. Also, a recent study
showed that MPA, but not progesterone (P), almost totally inhibits the
intracellular androgen receptor (iAR) (http://www.fasebj.org/cgi/
content/abstract/21/10/2285). Since iAR downregulates (decreases the
overall production of) bcl-2, a protein that strongly protects BC
cells from apoptosis (programmed cell death), then it is clear why MPA
is so dangerous (http://www.tbiomed.com/content/4/1/28). By blocking
a receptor that downregulates bcl-2, you end up with an increased
production of bcl-2. Basically, for BC to develop the rate of growth
must be greater than the rate of cell death. For some of those women
who are protected because of their internal balance, the addition of
MPA is all that is needed to change from being protected from BC to
being susceptible to BC. Also, those women who had undiagnosed BC
already growing within them would have an increased population growth
rate of their BC when bcl-2 is increased. All of this was observed in
the WHI study. Finally, even women taking MPA for birth control would
be expected to have an increased rate of BC, but the rate of increase
would be much lower than what it is for post-menopausal women because
of the protective effect of the high level of all of the hormones
found naturally in younger women.

What is interesting is that all of the evidence shows that unlike MPA,
P actually decreases the amount of bcl-2 produced (http://
www.fasebj.org/cgi/content/abstract/21/10/2285). Therefore while HRT
with MPA increases the rate of BC, HRT with P would be expected to
decrease the rate of BC. The real puzzle here is why hasn't the FDA
banned MPA already.

Ed Friedman

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