Breast cancer, although we think of it as one disease, it is really of many different types each with differing origins, response to treatment and risk factors. Women tend to be more worried about breast cancer than heart disease—most of us know some woman who has had breast cancer. Almost one woman of every nine white (western, privileged) women will get breast cancer in her lifetime—Asian women and those from less industrialized or more rural and poorer countries have lower breast cancer risks.
There are a number of breast cancer risk factors over which we have little control. A very few women inherit breast cancer risks because of a close relative with it (mother, sister, cousin, grandmother, aunt) or because of having the gene for BRCA1 or BRCA2. However, 80% of women who develop breast cancer have no known family history. We also cannot control our age at menarche—it is a risk to start menstruating at younger than 11-12 years. Women who have menopause at age 55 or later are also at slightly greater risk for breast cancer.
Although we talk of breast cancer prevention, screening mammograms, regularly doing breast self-examinations or having yearly health-care-provider breast examinations are finding a breast cancer that is already there. We also know many things that decrease our risks for breast cancer. These include maintaining a normal weight (BMI 18.5-24.9) throughout our lives, exercising moderately for 30 minutes a day, avoiding regular alcohol intake, using other barrier/vaginal spermicide contraception rather than COC, patch or ring and avoiding use of menopausal hormone therapy (OHT—combined estrogen and progestin/progesterone) especially in perimenopause or 5 years into menopause. However, if OHT is needed transdermal estradiol (patch, gel, or cream) with progesterone (rather than progestins like medroxyprogesterone) will not increase breast cancer risks (1).
CeMCOR believes that silent ovulatory disturbances having normal amounts of estrogen (during regular cycles) but not normal amounts of progesterone, pose the major unrecognized risk for breast cancer. Ovulatory disturbances are common and not recognized (2) and are associated with other health risks such as bone loss (3). A combination of socially and emotionally supportive environments and healthy life styles with maintained ovulation is likely to lead to true breast cancer prevention.
(1) Fournier A, Berrino F, Clavel-Chapelon F. Unequal risks for breast cancer associated with different hormone replacement therapies: results from the E3N cohort study. Breast Cancer Res Treat 2008 Jan;107(1):103-11.
(2) Prior JC, Naess M, Langhammer A, Forsmo S. The point prevalence of ovulation in a large population-based sample of spontaneously, regularly menstruating women. The HUNT Study, Norway. Endocrine Society , OR 19-1 6573. 2013.
(3) Li D, Hitchcock CL, Barr SI, Yu T, Prior JC. Negative Spinal Bone Mineral Density Changes and Subclinical Ovulatory Disturbances--Prospective Data in Healthy Premenopausal Women With Regular Menstrual Cycles. Epidemiol Rev 2014;36(137):147.