Apparently, BRCA1 secretes a protein that inhibits certain cells from uncontrolled division and growth. One of the more interesting theories regarding that steady rise in breast cancer rates was recently discussed in an article written by Rosie Mestel for Health magazine. Briefly, evolutionary biologists collecting and recording salivary estrogen levels have recognized patterns of low feminine fertility correlated with famine. Lower estrogen levels relate to temporary infertility. We can document that, even for women in lower income brackets, general nutrition in America improved steadily over those years.
Improved nutrition leads to increased exposure over a lifetime to estrogens.
We are living a very different lifestyle than that in which our bodies developed. Dr. Malcolm Pike, head of preventive medicine at the University of Southern California, has even suggested artificially adjusting women's hormone levels from puberty to death, with occasional time-outs for childbirth, as a preventive measure in the fight against breast and ovarian cancers. In fact, women benefit from the estrogen in their bodies. But too much of a good thing can wreak havoc with the rest of our physiological system. Estrogens significantly increase the risk of developing breast and ovarian cancers.