© 2001 by Oxford University Press
Journal of the National Cancer Institute, Vol. 93, No. 10, 731,
May 16, 2001
© 2001 Oxford University Press
MEMORANDUM FOR: Science Writers and Editors on the Journal Press List
No Link Found Between High Rates of Breast Cancer in the Northeastern States and the Chemicals DDE and PCBs
May 10, 2001 (EMBARGOED FOR RELEASE 4 P.M. ET May 15)
An analysis of combined data from five recent studies concludes that exposure to the chemicals DDE or PCBs is not associated with the high rates of breast cancer observed in the northeastern United States.
DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] is the major metabolic product of the pesticide DDT, and PCBs (polychlorinated biphenyls) are a group of industrial chemicals made and used in the United States until the 1970s. These compounds accumulate in fatty tissues, resist metabolic breakdown, and are found in human blood and breast milk. Starting in 1993, five studies were sponsored by the National Cancer Institute and the National Institute of Environmental Health Sciences to determine whether an increased risk of breast cancer was associated with exposure to these and related compounds. All five studies concluded that there was no evidence of an overall association. However, suggestions of effects in specific subgroups were observed, and although all of the studies are considered to be large, they had limited power to perform these subgroup analyses. Therefore, Francine Laden, Sc.D., Brigham & Women’s Hospital and Harvard Medical School, and co-authors combined and reanalyzed the primary data by use of a standardized approach. Their results appear in the May 16 issue of the Journal of the National Cancer Institute.
The five studies involved a total of 1400 breast cancer patients and 1642 control patients. Two of the studies enrolled women in New York state, one involved Connecticut, one Maryland, and one study used the nationwide Nurses’ Health Study cohort, of which more than half of the women live in the northeastern states or Maryland. Blood was drawn from all participants and analyzed for the presence of DDE and PCBs.
The authors’ analysis of the combined data does not support an association between plasma or serum concentrations of DDE and total PCBs and an increased risk of breast cancer. In the combined analyses, an influence of body mass index (BMI) was suggested, but there was no evidence of a dose–response relationship. Specifically, the odds ratios for breast cancer and exposure to high PCB levels among women in the middle category of BMI (25–29.9 kg/m2) were elevated, and those for the heaviest women tended toward a protective effect. Thus, the authors conclude that exposure to DDE and PCBs, as measured in adult women, is unlikely to explain the high rates of breast cancer experienced in the northeastern United States.
Contact: Jessica Collins, Brigham & Women’s Public Affairs Office, (617) 732-5008; fax: (617) 437-1924; jcollins3{at}partners.org.
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Laden F, Collman G, Iwamoto K, Alberg AJ, Berkowitz GS, Freudenheim JL, et al. 1,1-Dichloro-2,2-bis(p-chlorophenyl)ethylene and polychlorinated biphenyls and breast cancer: combined analysis of five U.S. studies. J Natl Cancer Inst 2001;93:768–76.
Note: This memo to reporters is from the Journal staff and is not an official release of the National Cancer Institute (NCI) or Oxford University Press (OUP) nor does it reflect NCI or OUP policy. In addition, unless otherwise stated, all articles and items published in the Journal reflect the individual views of the authors and not necessarily the official points of view held by NCI, any other component of the U.S. government, OUP, or the organizations with which the authors are affiliated. Neither NCI nor any other component of the U.S. government nor OUP assumes any responsibility for the completeness of the articles or other items or the accuracy of the conclusions reached therein.
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