The LC from Silver Cross Hospital In Joilet, IL (sorry, I didn't see your
name) wrote:

 

"To me, it's not logical that the density would cause a greater risk for
breast cancer."

 

I agree with your statement!  We can't say that the density is a *cause* for
the increased risk based on this study.  I think that we must be careful to
interpret this study using the idea that there was an *association* between
having mammographically dense breast tissue and developing breast cancer.
The study was only an observational study and therefore we cannot assume
*causation*.  In other words, just because we observe more people carrying
umbrellas on days that it rains, it doesn't mean that the umbrellas *cause*
it to rain-only that there is an *association* between umbrellas and rain.
Medical science is still working out the details of the association between
breast density and cancer.  (Fortunately, I think they finally have gotten
that umbrella and rain association figured out.)  :-)

 

We also see a link between early age at onset of menses and a higher risk of
breast cancer (often occurring more than several decades later!)  It seems
that there may be some link between the hormonal milieu at the time of the
development of the breast and the later risk of developing breast cancer.
Perhaps women who have higher levels of hormones during pubertal development
(as indicated at the time by earlier onset of menses) end up also developing
denser breast tissue due to the presence of these hormones during puberty.
Perhaps, the presence of these hormones at the time of breast development
also ultimately places these women at a higher risk of breast cancer.  In
the context of this theory- the early menses and dense breast tissue
themselves did not *cause* her to be at a higher risk of breast cancer, but
were *associated with* (or can perhaps be considered markers for) a higher
risk of breast cancer.

 

Another interesting tidbit of info regarding breast cancer risk is that
women with lower bone densities seem to be at a lower risk of developing
breast cancer.  Again- it's not that we think that the low bone density
itself is causing the lower risk.  Rather there is a theory that the low
bone density is a marker for lower hormone levels (during some apparently
crucial point in development) and that these low hormone levels make women
at a lower risk of developing breast cancer.

 

Warmly, Jayne (in cloudy Syracuse, NY, USA where it rains so often that we
should have been a prime location for research on that association between
umbrellas and rain!)

 

Jayne R Charlamb, MD, IBCLC

Breast Care Center

SUNY Upstate Medical University

Syracuse, New York 13202


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