Many women wonder if a 'healthy' diet will lower their risk of getting breast cancer. According to the NCI's current prevention site (go here) the only good dietary advice is to avoid obesity and limit alcohol. another recent summary on diet is here. (Postmenopausal women weighing over 82.2 kg (180 pounds) with those under 58.7 kg, (129 pounds)  have a relative risk (RR) that was 2.85. The RR for women consuming approximately four alcoholic drinks per day compared with nondrinkers is 1.32. The RR increases by 7%  for each drink per day.

A recent review of all diet studies and breast cancer came to the same conclusion (see below)  and read the section  on prevention. There is evidence that women who already have breast cancer will benefit from eating a healthy diet and getting exercise (go here). But another study that found that women who have breast cancer and then try to eat 'healthy' do not benefit (go here). The large trial of low fat diet did not lower the risk of breast, colon or any cancer (see here.) A recent study showed no significant benefit from B vitamins in preventing cancer in women (go here).

For a  discussion of appropriate diet and nutritional needs and exercise if you already have cancer read the section on diet/nutrition,  and on alternative health diets.

Michels. Cancer 2007;109:2712

The role of diet for the risk of breast cancer is of great interest as a potentially modifiable risk factor. The evidence from prospective observational studies was reviewed and summarized on selected dietary factors, gene-diet interactions, and breast cancer incidence. Dietary factors were considered that, based on their nutritional constituents, are of particular interest in the context of breast cancer: fat intake, biomarkers of fat intake, fruit and vegetable consumption, antioxidant vitamins (vitamins A, C, E, and beta-carotene), serum antioxidants, carbohydrate intake, glycemic index and glycemic load, dairy consumption (including vitamin D), consumption of soy products and isoflavones, green tea, heterocyclic amines, and adolescent diet. The PubMed database was searched for all prospective studies that relate these dietary items to the incidence of breast cancer or consider gene-diet interactions.

Among the prospective epidemiologic studies conducted on diet and breast cancer incidence and gene-diet interactions and breast cancer incidence, to date there is no association that is consistent, strong, and statistically significant, with the exception of alcohol intake, overweight, and weight gain. The apparent lack of association between diet and breast cancer may reflect a true absence of association between diet and breast cancer incidence or may be due to measurement error exceeding the variation in the diet studied, lack of sufficient follow-up, and focus on an age range of low susceptibility. The risk of breast cancer can be reduced by avoidance of weight gain in adulthood and limiting the consumption of alcohol.

As an organization that promotes the importance of evidence-based medicine, the Susan G. Komen for the Cure is eager to see science yield more answers that will eventually lead to new ways to prevent breast cancer. We have made progress in the US in expanding life-saving access to breast cancer screening and treatment but not in substantially reducing incidence. Many of the identified risk factors, including family history of the disease, age at menarche and menopause, parity, breast density, and age at a first full-term pregnancy, cannot be readily modified. Pursuing new evidence of risk factors that can be changed is a crucial priority if we are to achieve our vision of a world without breast cancer. The preliminary report this year that US breast cancer incidence declined by 7% - 14,000 women - in 2003 and that the drop may be due to reduced use of hormone replacement therapy[1] reinforces our commitment to studies of other exogenous chemicals, behaviors that affect hormones, and other factors with the potential to significantly affect risk for many thousands of women.

To advance that goal, in 2004, Komen commissioned the Environmental Factors and Breast Cancer Science Review with Massachusetts-based Silent Spring Institute and their collaborating partners at Harvard University, Roswell Park Cancer Institute, and the University of Southern California to collect and assess existing published scientific reports on possible links between specific environmental factors and breast cancer. In its first year the review targeted epidemiologic studies on environmental pollutants, dietary factors, body size, physical activity, and interactions of these factors with various genetic polymorphisms, and the group reviewed toxicology studies to identify chemicals that cause mammary tumors in animals. Reviews are currently under way on additional topic areas: the toxicology of endocrine disruptors, perinatal and early life exposures, nonhormonal pharmaceuticals, tobacco smoke, occupational exposures, light at night, and psychological stress. Topics were chosen to reflect areas of active research with particular promise for identifying new opportunities for prevention.

The chief goal of the Silent Spring Institute study was to evaluate published research to determine what is known and what is not known about the possible link between environmental factors and the incidence of breast cancer. Breast cancer is an extremely complex disease, caused by the interaction of multiple factors, including exposure to carcinogens, genetics, various aspects of lifestyle, and income disparities, among many others. These factors, coupled with the timing, dose, and duration of harmful exposures, further complicate our understanding of and ability to study an individual's risk for developing breast cancer. Understanding the weight of evidence in this multifaceted area of science can guide public information, public health policy, and future research.

The outcomes of the Silent Spring Institute study are of particular value to the scientific research and public policy communities. The study provides:

The most comprehensive, searchable database of potential mammary carcinogens, based on animal studies, including a list of 216 carcinogens and more detailed information on 97 with the most widespread exposure.

A searchable database containing summaries and critical reviews of significant existing and ongoing epidemiologic research regarding possible links between breast cancer and diet, physical activity, body size, environmental pollutants, and gene-environment interactions with these factors. The critical review articles that integrate and evaluate the results contained in the databases are included in this special issue, and the databases are accessible online at www.komen.org/environment and www.silentspring.org/sciencereview

The study results are especially useful in pointing out where there is consensus within the scientific community on the relationship between environmental factors and breast cancer and where additional research or improved research methods are required. As an advocacy organization, Komen has identified several core messages from the science that will inform our work. The results provide consistent evidence to reinforce the importance of physical activity and its potential to lower a woman's risk of developing breast cancer. Conversely, although alcohol consumption increases breast cancer risk, studies of other aspects of diet do not currently support clear recommendations related to breast cancer risk reduction. For environmental pollutants, toxicologic studies raise concerns about a large number of chemicals for which exposure is common; the epidemiologic evidence is beginning to catch up, although this area has received relatively little attention and gaps in our knowledge remain.

The results underscore the need for further research on the relation between dietary factors, environmental pollutants, and breast cancer risk. As a direct follow-up to the review, Komen announced a new Focused Areas of Study program that will support at least $5 million in grants to develop new environmental research methods. In addition, Komen continues to fund environmental projects as part of its investigator-initiated grants program, and Komen also supports and champions agencies such as the National Cancer Institute (NCI), the Environmental Protection Agency (EPA), and the National Institute of Environmental Health Sciences (NIEHS) that continue to investigate the impact of the environment on breast cancer incidence.