The Review Is In: Lifestyle Changes Prevent Breast Cancer

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This article was written by Allison Bland.

Experts agree that diet and nutrition can reduce risk of many diseases, including different types of cancer and chronic disease. A recent update to a 2007 report by the American Institute for Cancer Research/World Cancer Research Fund (AICR/WCRF) concludes that breast cancer deaths can be prevented by physical activity, breast feeding, a healthy diet and other preventative measures. The study is an update to the breast cancer chapter of Food, Nutrition, Physical Activity and the Prevention of Cancer: a Global Perspective [1]. Earlier conclusions were based on data from 873 studies evaluating the relationship between diet, physical activity, obesity and cancer [2]. The 2009 update includes evidence from an additional 81 studies.

The report estimates that over 70,000 breast cancer cases in the U.S. — 40% of cases every year– could be avoided every year by simple lifestyle changes. The update reinforces the following AICR recommendations:

• Due to the link between excess body fat and cancer, people should aim to be as lean as possible without being underweight.
• Be physically active for at least 30 minutes daily.
• If you drink, limit alchohol consumption to two drinks a day for a man and one for a woman.
• Mothers should breastfeed exclusively for up to six months after birth.

The report did not examine other protective factors that may overlap and contribute to breast cancer, such as the effect of taking postmenopausal hormone therapy and oral contraceptives, or risk factors, some of which cannot be avoided, such as genetic background or certain environmental factors.

The AICR recommends a mostly plant-based diet with limited consumption of salt, red meats and alcoholic drinks. The report does not provide a decisive picture of particular food groups that can reduce the incidence of cancer. As of 2006, the largest ever clinical trial of low-fat diet showed that longer term follow-up was needed to determine whether reducing total fat intake had a signficant impact on the incidence of breast cancer [2].

Even so, following the AICR’s recommendations can lead to better prevention practices: a study from Johns Hopkins University School of Medicine found that obese women are less likely to undergo regular mammography, which is key to screening breast cancer and lowering mortality rates [3]. The National Cancer Institute provides risk profiles and other tools that examine multiple factors that impact your risk to develop breast cancer.

The AICR/WCRF report — Food, Nutrition, Physical Activity and the Prevention of Cancer: a Global Perspective — is the most comprehensive report on diet and cancer ever compiled. Over 7,000 studies were independently reviewed, compiled and presented to an expert panel of 21 world-renowed scientists, who evaluated the data and developed recommendations for cancer prevention.

The report on breast cancer is part of the Continuous Update Project, which continuously updates the findings of the AICR/WCRF 2007 report [1]. This allows for cancer prevention information that is always based on the latest research. Breast cancer is the first type of cancer researchers have reviewed evidence on as part of the update project. They have started reviewing data on colorectal cancer and prostate cancer, and the results are expected early next year. The long-term goal of the Continuous Update Project is to continually update evidence on all types of cancer.

About the author: Allison Bland is a communications fellow at Research!America and a graduate of McGill University with degrees in English and History of Science. She is interested in science and health communication on the web.

References

1. Food, Nutrition, Physical Activity and the Prevention of Cancer: a Global Perspective. World Cancer Research Fund/American Institute for Cancer Research. 2007 Nov 1.
2. Prentice et al. Low-fat dietary pattern and risk of invasive breast cancer: the Women’s Health Initiative Randomized Controlled Dietary Modification Trial. JAMA. 2006 Feb 8;295(6):629-42.
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3. Maruthur et al. Obesity and mammography: a systematic review and meta-analysis. J Gen Intern Med. 2009 May;24(5):665-77. Epub 2009 Mar 11.
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