Estrogens are broken down into several different metabolites that can impact cancer development. One metabolite, 2-hydroxyestrone, has been found to inhibit cancer growth. Another, 16-alpha-hydroxyestrone, encourages tumor development. A woman’s "biochemical individuality" determines which of these metabolites predominates. Studies have shown that measuring the ratio of these two metabolites provides an important indication of risk for future development of estrogen-sensitive cancers.
Encouragingly, these studies also show that this risk is modifiable!