New Study Finds No Link Between High-Fat Diets and Breast Cancer (dateline November 6, 2000)
Contrary to previous data which suggests that a fatty diet may increase the risk of breast cancer by raising hormone levels, a new study of nearly 400 women finds no link between a high-fat diet and breast cancer. Researchers say that the results give women one less thing to worry about when it comes to breast cancer. However, they are also quick to point out that high-fat diets can increase the risk for other adverse health effects, such as heart disease.
Up until now, scientists have theorized that high-fat diets increase the level of estrogen in the body. Since higher estrogen levels have been associated with increased breast cancer risk, scientists believed that high-fat diets increased the risk for breast cancer.
However, according to the new study, published in the November 2000 issue of the Journal of Clinical Oncology, high-fat diets do not increase estrogen levels in the body. In fact, in the 381 women the researchers followed, high-fat diets averaged over four to five years were associated with a decrease in estrogen levels in the body.
According to Michelle Holmes, MD, Assistant Professor of Medicine at Harvard School of Medicine, the study results do not suggest that women should consume high amounts of fat, since they may increase the risk for other diseases, such as heart disease or colorectal cancer.
While future studies will continue to explore the link between diet and breast cancer, the results of this study suggest that eating a low-fat diet is not an effective way of preventing breast cancer. While maintaining a low-fat diet can promote overall health, women at high risk of breast cancer (such as those with a strong family history or those who test positive for BRCA gene mutations) may wish to explore other preventive measures to help guard against the disease.
Preventive measures for women at high risk of breast cancer include:
- Close monitoring with clinical breast exams and mammography to help detect breast cancer in its earliest stages
- The drug tamoxifen (an anti-estrogen)
- Prophylactic mastectomy (preventive breast removal)
Physicians believe that the link between diet and breast cancer will continue to be controversial. 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 Japan). However, 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 non-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
- The study, "Dietary Fat Intake and Endogenous Sex Steroid Hormone Levels in Postmenopausal Women," is published in the November 2000 issue of the Journal of Clinical Oncology (Vol.18, Issue 21). An abstract of the study is available at http://www.jco.org/cgi/content/abstract/18/21/3668
- 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