85% of cancers occur in women with no family history of breast cancer. The major risk factors remain gender and age. The incidence of breast cancer is decreasing, likely due to increased screening, as well as decreased use of synthetic hormone replacement.
The hormones we produce naturally (estradiol, progesterone, and testosterone) each have unique chemical structures. They join with their respective receptors or “gates” on the cell membrane, like a key into a lock, and instruct our cells how to function. Synthetic hormones have different chemical structures than our natural hormones and cannot join to receptors properly. Negative effects often result. The hormones used in the Women’s Health Initiative Study, Premarin and Provera (both synthetic) increased the risk of breast cancer by 29%. The increase may have been largely due to Provera which blocks up to 80-95% of the testosterone receptors. Natural or bioidentical testosterone is actually protective to the breast so it doesn’t help to block testosterone receptors! (Bioidentical testosterone has the same exact chemical structure, as the testosterone that the body produces naturally). Progesterone is also protective to the breast in women that do not carry the BRCA mutations. Provera of course also blocks the progesterone receptor. See Dr. Edward Friedman’s book “The New Testosterone Treatment- How You and Your Doctor Can Fight Breast Cancer, Prostate Cancer, and Alzheimer’s” 2013.