Soy and PhytoestrogensPhytoestrogens are estrogen-like substances found in plant products. These include soybeans, black cohosh (an herb), whole wheat, berries, and flaxseed. In general, the evidence on their effects on breast cancer is unclear. Most research has focused on soy. In general, Asian women have a lower incidence of reproductive and breast cancers as well as a higher intake of soy. For example, a 2000 Asian study reported an association between high levels of soy compounds in the urine and a significantly lower risk for breast cancer. A 2001 study in China reported that high soy intake during adolescence was associated with a lower risk for breast cancer later on. The effects of phytoestrogens, however, in all cases are far from settled. Of concern are studies that report breast cell proliferation with low levels of genistein (one of the important isoflavones compounds in soy). In one study, the compound actually reversed the protective properties of tamoxifen, a drug used to prevent breast cancer in high-risk women. In general, women at risk for breast cancer, especially women who take hormone replacement therapy, should avoid consuming large amounts of plant products with high levels of phytoestrogens until more is known about their effects. |
Avoiding Alcohol
Several studies have reported a higher risk for breast cancer in women who consume alcohol. A well-conducted 2003 analysis of many of these studies suggested that for every daily drink there was a 7% increase in breast cancer. By age 80, women who consumed two drinks a day had a 10% increased risk for developing breast cancer. Based on these findings, researchers suggested that about 4% of breast cancer cases in developed nations may be attributed to alcohol. (Women who drink and who take hormone replacement therapy have an even greater risk.) Some research indicates that alcohol in such amounts increases levels of growth factors that can stimulate breast cancer cells. However, light to moderate drinking has benefits for the heart that most likely outweigh the cancer risk in most women who have no other risk factors for breast cancer or alcohol abuse.
Breastfeeding
Several studies have reported that breastfeeding is associated with a lower risk for cancer in premenopausal women. Some studies also suggest that some protective effect from breastfeeding may last beyond menopause. Studies also indicate that the longer the mother breastfeeds, the better. In fact, some experts believe the high rates of breast cancer in developed countries may be partly due to a lack of or shorter duration of breastfeeding.
Specific Preventive Measures for High-Risk Women
Lifestyle Factors. Premenopausal women at elevated risk, usually because of family history, should take as many preventive measures as possible, starting at an early age. The following life-style choices may be beneficial:
- Exercising and eating healthily is the first essential rule.
- High-risk premenopausal women may choose alternatives to oral contraceptives and, if feasible, consider having children early in their life.
- High-risk postmenopausal women may want to forego hormone replacement therapy.
- Any woman at high risk for breast cancer might consider avoiding alcohol or drinking it sparingly.
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