If you are a woman living in the United States, you have a one in eight chance of developing invasive breast cancer sometime during your lifetime. Nearly 40,000 American women will die from this disease during 2010. Since 70 to 80 percent of cases occur in women who have no family history of breast cancer, genetics apparently play a smaller role than is commonly believed. Breast cancer causes higher mortality in Western countries than in other regions, so lifestyle may be a significant contributor.
Risk Factors
The two most significant risk factors for breast cancer are female gender and advancing age. Others include a personal or family history of breast cancer, starting your period before age 12, starting menopause after age 55, possessing either the BRCA1 or BRCA2 gene, prior radiation exposure to your chest, having your first child after age 35, obesity, alcohol consumption and taking hormone replacement therapy after menopause. According to a 2007 study in the "Journal of the National Cancer Institute," dietary fat may be another risk factor for breast cancer, but consensus is still lacking.
Dietary Fat
Although being overweight increases your risk for breast cancer, the connection between dietary fat and breast cancer is less clear. Results of studies that examine this relationship are mixed, probably because the data is confounded by multiple variables. Women who consume high-fat diets may unwittingly ingest other cancer-causing agents, such as fat-soluble toxins. It is difficult to design a study comparing low-fat to high-fat diets in a country where the majority of women consume too much fat. Most women who are obese -- an independent risk factor for breast cancer -- consume high-fat diets, so assigning cancer risk exclusively to dietary fat intake is statistically challenging. Finally, the total amount of fat consumed may not be as important as the balance between different kinds of fats, such as saturated, polyunsaturated and monounsaturated fats, or omega-3 and omega-6 fatty acids.
Fats and Inflammation
In 2006, researchers in Switzerland reported that total dietary fat and the percentage of calories obtained from dietary fat could predict the degree of inflammation in children's tissues. Studies in adults demonstrate similar findings. Fatty acids undergo oxidation in your bloodstream and tissues, setting the stage for cellular injury and inflammation. A 2002 review in "The Psychiatric Times" links chronic inflammation to the initiation and progression of cancer.
Good Fats
To further complicate the discussion about dietary fats and breast cancer risk, it appears that some fats actually seem to confer protection from breast cancer. For example, in Mediterranean countries, where women typically consume at least as much total fat as American women, the incidence of breast cancer is much lower. The disparity between these groups may be explained by the fact that the majority of fat consumed in Mediterranean regions comes from olive oil, a monounsaturated fat source. Fish oils may offer the same protection from breast cancer that olive oil does.
Recommendations
Even though the evidence tying dietary fat to breast cancer isn't conclusive, the data is sufficient to prompt caution. Saturated and polyunsaturated fats, particularly those containing omega-6 fatty acids, have been shown to increase the growth of breast tumors in animal studies. Some human studies have demonstrated a similar association between dietary fat and breast cancer. Given what is already known about the health risks of excess dietary fat, you should limit your fat intake to less than 30 percent of your total calories, include more monounsaturated fats in your diet, eat more fruits, vegetables and whole grains and exercise every day.
References
- BreastCancer.org: Breast Cancer Statistics
- "Breast Cancer"; Epidemiology of Breast Cancer in Japan; Tominaga S, Kuroishi T; 1995
- "Journal of the National Cancer Institute"; Dietary Fat and Postmenopausal Invasive Breast Cancer in the National Institutes of Health--AARP Diet and Health Study Cohort; Thiebaut A, et al.; 2007
- "The American Journal of Clinical Nutrition"; Dietary intakes of fat and antioxidant vitamins are predictors of subclinical inflammation in overweight Swiss children; Aeberli I, et al.; 2006
- "The Psychiatric Times"; Chronic Inflammation and Cancer; Shacter E; 2002
- The Sprecher Institute for Comparative Cancer Research: Dietary Fat and the Risk of Breast Cancer
