Sex Hormones & Breast Cancer: Too Much of a Good Thing Isn't

You remember Goldilocks, right?  She didn't like her porridge too hot or too cold but rather just right.  Likewise, she didn't like her bed too hard or too soft, but rather just right.  It would appear that in many facets of life, our health is based upon a similar premise.  More importantly, many of these factors can be easily measured.  

Blood pressure that's too low leads to passing out while blood pressure that's too high can increase one's risk for stroke, heart attack & kidney failure.  Likewise, not enough blood is considered anemia which is associated with feeling weak & tired while too much blood is considered polycythemia and is associated with thrombotic events. Not enough thyroid hormone is just as bad as too much.

Earlier this summer, I reported on a study demonstrating a sweet spot in the normal reference range for IGF-1, a measure of growth hormone, when evaluating for mortality.  In a similar manner, in a study published just last week, authors noted that post-menopausal women with the highest quintile of estrogens, androgens, or growth hormone (as measured by IGF-1) had an increase risk of breast cancer.  More importantly, the greater the number of hormones above the mean, the greater one's risk of breast cancer.

For now, this association of high levels of sex hormones with an increase risk of breast cancer in post-menopausal women is just that, an association derived by comparing 265 cases to 541 matched controls from the Nurses' Health Study.  While we do not have any evidence of cause & effect, this study suggests that we should not blindly treat all women with the exact same dose of hormone therapy, regardless of size and individual metabolism.  Instead, we should consider measuring hormone levels, something that can easily be performed by either drawing blood or checking salivary levels.  Just a thought!

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