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Pre-menopausal women who frequently consume red meat may be at higher risk of developing a certain type of
breast cancer than pre-menopausal women who consume less red meat, according to the results of a new study. Most
women who develop breast cancer have already reached menopause, but
a small percentage develop the disease in earlier years. Past studies about the association between red meat and
breast cancer risk have largely been inconclusive. Researchers of the current study do not know why pre-menopausal
women who consume red meat several times a week may have a greater risk of breast cancer and say that further
researcher is needed to explore this apparent connection.
"This study suggests that dietary factors may be related to a woman's chance of developing this type of
breast cancer, a disease that is on the rise in American women," said lead author, Eunyoung Cho, Sc.D, a
researcher at Brigham and Women's Hospital in Boston, Massachusetts, in a news release. The study was
published in the November 13, 2006 issue of the Archives of Internal Medicine.
To conduct the study, researchers studied 90,659 pre-menopausal female nurses between the ages of 26 to 46 who
are participating in the Nurses' Health Study II. The researchers followed the women from 1991 through 2003
and tracked their red meat consumption through a series of questionnaires. They also monitored whether
the women developed breast cancer through the women's self-reports and hospital records. In total, 1,021 of
the women developed breast cancer.
Upon further analysis, the researchers found that how much red meat women consumed appeared to be linked to
their breast cancer risk level. For example, women who consumed more than one and a half servings of
red meat per day had nearly double the risk of a certain type of breast cancer compared with those
with the lowest intake of red meat, which was less than three servings per week.
It should be noted that red meat only appeared to increase the risk a certain type of breast cancer called
hormone-receptor positive breast cancer. Many breast cancer cells contain estrogen or progesterone receptors; these
cancers are called estrogen-receptor positive or progesterone-receptor positive (broadly, either are
called hormone receptor positive breast cancer). Approximately 80% of breast cancers are estrogen
receptor-positive; that is, they contain estrogen receptors. The remaining 20% are estrogen
receptor-negative-they do not contain estrogen receptors. Out of the 1,021 women in the studied who
developed breast cancer, 512 of them had hormone-receptor positive breast cancer.
Previous studies on diet and breast cancer have largely yielded inconclusive results. In a 2002 British study
of women who came to Britain from India, Pakistan, and Bangladesh, researchers found that those women who were
lifelong vegetarians had a lower risk of developing breast cancer than those women who consumed meat. However, a 2000
study of nearly 400 women found no link between a high-fat diet and breast cancer. The researchers of the current
study argue that many past studies focused on diet in women who had reached mid life or later, as opposed to younger women.
"The reason why the amount of red meat consumed by a pre-menopausal women was related to her breast cancer risk
is unknown, but this study shows that it has a strong association and that more research should be done to further explore
this connection," said Cho.
The link between diet and breast cancer will likely continue to be controversial. However, researchers have found
that there is a much higher incidence of breast cancer in areas with high fat diets (such as the United States) than
areas with low-fat diets (such as Asia).
Researchers have identified other factors that seem to play a larger role in determining breast cancer risk (although
80% of women diagnosed with breast cancer have no known risk factors).
Risk factors for breast cancer include:
- Advancing age
- Family history of breast cancer
- Personal history of biopsy revealing pre-cancerous conditions, such as lobular carcinoma in situ (LCIS)
- Genetic mutations of the BRCA1 or BRCA2 genes
- Early onset of menstruation (before age 12)
- Late menopause (after age 50)
- Not having children, or having children after age 30
Additional Resources and References
- The study, Red Meat Intake and Risk of Breast Cancer Among Premenopausal Women, was published in the November 13, 2006 issue of Archives of Internal Medicine, http://archinte.ama-assn.org/
- The November 13, 2006 Brigham and Women's Hospital news release, "Red Meat Consumption Associated with Increased Risk for Breast Cancer," was published on the hospital's website, http://www.brighamandwomens.org/
- To learn more about the risk factors for breast cancer, including links between diet and breast cancer risk, please visit http://www.imaginis.com/breasthealth/bc_risks.asp
- The September 29, 2002 Imaginis.com report, "Study: Vegetarians May be at Lower Risk of Developing Breast Cancer," is available at http://www.imaginis.com/breasthealth/news/news9.29.02.asp
- The November 6, 2000 Imaginis.com report, "New Study Finds No Link Between High-Fat Diets and Breast Cancer," is available at http://www.imaginis.com/breasthealth/news/news11.06.00.asp
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