According to the National Cancer Institute, more than 200,000 women developed breast cancer in 2010. Most women were diagnosed at the age of 61 with a median age of death of 68 years of age. Cancer of the breast affects all races, with greatest incidence in blacks and whites, with lower prevalence in Hispanics and Asians. A report by Cuzick and colleagues found that only a minority of women with an elevated risk of breast cancer opt to take the standard prevention drug, tamoxifen, due to its side effects, incomplete efficacy and lack of a demonstrated survival advantage.
Flaxseed
Flaxseed comes from the plant Linum usitatissimum. People use flaxseed to alleviate or treat many conditions, including gastroinestinal distress, irritable bowel syndrome, and high cholesterol. Flaxseed contains omega-3 fatty acids and phytoestrogenic lignans.
Flaxseed and Breast Cancer
A systematic literature review by the American Institute for Cancer Research found that 10 g to 30 g of flaxseed a day, or the equivalent of a few tablespoons, positively altered estrogen levels in ways that could protect against breast cancer. An in-depth report by the American Institute for Cancer Research said that flaxseed decreases the growth of estrogen receptor positive and estrogen receptor negative breast cancers in rodent models. Animal models also suggest that flaxseed consumption does not interfere with tamoxifen, but instead may enhance its effect.
Omega Fatty Acids and Breast Cancer
Flaxseed contains a significant amount of omega-3 fatty acids, which have independently been shown to alter breast cancer risk. The American Institute for Cancer Research reports that omega-3 fatty acids produce an anti-inflammatory effect, which could positively modify breast tissue milieu.
Lignans and Breast Cancer
Phytoestrogens compete with estrogen for estrogen receptor binding. For this reason, phytoestrogens, such as the lignans found in flax seed, reduce breast cancer risk. In a review by the AICR, two human studies found that increased serum levels of flaxseed lignans reduce breast cancer risk, two had no effect, and one both increased and decreased risk depending on the level of intake. In the same systematic literature review, consumption of flaxseed lignans reduced breast cancer risk in three studies, had no effect in three studies, and only reduced post-menopausal breast cancer risk in one study.
References
- AICR: In Depth: Flaxseed and Breast Cancer
- National Institutes of Health: Medline Plus: Flaxseed
- National Center for Complementary and Alternative Medicine: Flaxseed and Flaxseed Oil
- "Journal of the National Cancer Institute"; Long-Term Results of Tamoxifen Prophylaxis for Breast Cancer---96---Month Follow-Up of the Randomized IBIS-I Trial; J Cuzick, JF Forbes, I Sestak, et al.; Feb. 2007
