Cancer publishes Silent Spring Institute's review of environmental factors and breast cancer

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We all carry a body burden from the chemical swirl of our environment. But when does that burden grow too heavy? Which chemicals can be tolerated, and which trigger or hasten the development of cancerous cells?

To help clarify the chemical risks for breast cancer, Silent Spring Institute has compiled the most comprehensive review to date of scientific research on environmental factors that may increase risk of the disease. The study findings—entitled “Environmental Factors in Breast Cancer”—appeared in the June 15, 2007 issue of the American Cancer Society’s journal Cancer.

The state-of-the-science review—commissioned by Susan G. Komen for the Cure and conducted by Silent Spring Institute in collaboration with researchers from Harvard University, Roswell Park Cancer Institute, and the University of Southern California—involved the collection and assessment of scientific studies on potential links between specific environmental factors and breast cancer.

The research team examined modifiable influences on breast cancer. The result of this portion of the work—the Epidemiology Reviews Database—includes critical reviews of approximately 450 primary epidemiologic research articles on breast cancer and diet, environmental pollutants, physical activity, and body size. This database, which includes articles published through June 2006, is updated periodically.

After synthesizing data from national and international sources, the researchers also identified 216 chemicals that cause mammary tumors in animals. They then used that information to create a searchable online database featuring detailed information on the carcinogens. The Mammary Carcinogens Review Database offers summary assessments of the carcinogenic potential of each chemical, data on mutagenicity, opportunities for exposure in the general population and for women at work, and other characteristics of chemical use, sources, and regulation. The database includes references to 900 studies.

“While it’s disturbing to learn that so many chemicals may be linked to breast cancer,” says Dr. Julia Brody, executive director of Silent Spring Institute, “we must remember that we have a great opportunity to save thousands of lives by identifying those links, limiting exposure, and finding safer alternatives. It’s critical that we integrate this information into policies that govern chemical exposures.”

Review Articles

Reviews and commentaries on the Environment and Breast Cancer Science Reviews databases were published in Environmental Factors in Breast Cancer, a supplement issue of Cancer.

Evidence from Humans
Environmental Pollutants and Breast Cancer: Epidemiologic Studies Brody, JG, KP Moysich, O Humblet, KR Attfield, GB Beehler, RA Rudel. 2007. Cancer, 109 (S12): 2667–2712. [online May 14, 2007, print June 15, 2007] Article (pdf), Summary (pdf)

Diet and Breast Cancer: A Review of the Prospective Observational Studies Michels, KB, AP Mohllajee, ER Bahmanyar, GB Beehler, KP Moysich, 2007. Cancer, 109 (S12): 2712–2749. [online May 14, 2007, print June 15, 2007] Article (pdf), Summary (pdf)

Evidence from Animals
Chemicals Causing Mammary Gland Tumors in Animals Signal New Directions for Epidemiology, Chemicals Testing, and Risk Assessment for Breast Cancer Prevention Rudel, RA, KR Attfield, J Schifano, JG Brody. 2007. Cancer, 109 (S12): 2635–2667. [online May 14, 2007, print June 15, 2007] Article (pdf), Summary (pdf)
Commentaries on the Science Reviews
Environment Pollutants, Diet, Physical Activity, Body Size, and Breast Cancer: Where Do We Stand in Research to Identify Opportunities for Prevention? Brody, JG, RA Rudel, KB Michels, KP Moysich, L Bernstein, KR Attfield, S Gray. 2007. Cancer, 109 (S12): 2627–2634. [online May 14, 2007, print June 15, 2007] Commentary (pdf), Summary (pdf)

Advocate Perspective: Advancing Science-Based Approaches to Breast Cancer Prevention Susan G. Komen for the Cure. 2007. Cancer, 109 (S12): 2750–2751. [online May 14, 2007, print June 15, 2007] Commentary (pdf)

Epidemiology Reviews Database

In a systematic search of scientific research indexed in the online medical resource PubMed, the research team identified 450 primary epidemiologic research articles on breast cancer and environmental pollutants, physical activity, body size, and prospective studies of dietary factors.

For each article, the Science Review database includes quick access to basic study information and critical assessments:

  • the bibliographic citation and abstract or a link to a copyrighted abstract;
  • information about the study population, exposure assessment method, study design, results, and analyses of ethnic minority populations, early life exposures, or interactions with inherited genes;
  • assessments of the study’s strengths and weaknesses; and
  • interpretation of the study’s results.

Articles are searchable by topic. In addition, the database includes about 50 citations to review articles, methods papers, and exposure assessments that aid in interpreting the primary research. The database includes studies of environmental pollutants published through June 2006 and in other topic areas through May 2005. Review methods are described in the review articles published in Cancer.

Body Size The evidence is now substantial that body size—including postmenopausal weight gain and a high waist-to-hip ratio—is associated with a higher breast cancer risk. Public health initiatives and research to identify the most effective strategies for preventing obesity later in life should be breast cancer priorities.
See Science Review • body size
Diet Studies that monitored diet before diagnosis do not provide consistent evidence of associations with breast cancer. The research team considered studies of fat intake; fruits and vegetables; antioxidant vitamins (A, C, E, and beta-carotene); serum antioxidants; carbohydrate intake; glycemic index and glycemic load; dairy consumption, including vitamin D; soy products and isoflavones; green tea; heterocyclic amines; and adolescent diet. But after reviewing the prospective epidemiologic studies conducted on diet and breast cancer incidence and gene-diet interactions and breast cancer incidence, the research team found no association that was consistent, strong, and statistically significant, with the exception of alcohol intake, overweight, and weight gain. The researchers noted that this apparent lack of association between diet and breast cancer may reflect a true absence of an association or weaknesses in the research methods, such as errors in measuring aspects of diet, lack of sufficient follow-up, and focus on diet in adulthood rather than early life. The research team emphasized that women can reduce their breast cancer risk b