Adipose organochlorine concentrations and risk of breast cancer among postmenopausal Danish women.
OBJECTIVE
Exposure to environmental organochlorines has been examined as a potential risk factor for human breast cancer with mixed results. Our purpose was to examine associations between organochlorines and the development of breast cancer in a large prospective study using stored adipose tissue.


METHODS
We conducted a nested case-control study of 409 postmenopausal women who developed breast cancer and 409 controls selected from the 29,875 women enrolled in the Danish Diet, Cancer, and Health cohort between 1993 and 1997. We measured concentrations of 14 pesticides and 18 polychlorinated biphenyls in adipose tissue, collected upon enrollment, and estimated relative risk (RR) of breast cancer using conditional logistic regression.


RESULTS
The results showed no higher risk of breast cancer among women with higher levels of any pesticides or polychlorinated biphenyls; the RR associated with the upper quartile of 1,1-dichloro-2, 2-bis(p-chlorophenyl)ethylene concentration was 0.7 [95% confidence interval (95% CI), 0.5-1.2] contrasting the lower quartile, and for the sum of polychlorinated biphenyls the similar risk was 1.1 (95% CI, 0.7-1.7). We observed a pattern of substantially lower risk of estrogen receptor-negative breast cancer in association with higher levels of most of the pesticides and polychlorinated biphenyls; the RR for the higher quartile of 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene was 0.1 (95% CI, 0.0-0.5) and for the sum of polychlorinated biphenyls it was 0.3 (95% CI, 0.1-0.9).


CONCLUSIONS
The results do not support that higher organochlorine body levels increase the risk of breast cancer in postmenopausal women. The interpretation of the inverse association for estrogen receptor-negative breast cancer is currently unclear.
Raaschou-Nielsen
Ole
O
Danish Cancer Society, Institute of Cancer Epidemiology, Strandboulevarden 49, 2100 Copenhagen, Denmark. ole@cancer.dk
Pavuk
Marian
M
Leblanc
Alain
A
Dumas
Pierre
P
Philippe Weber
Jean
J
Olsen
Anja
A
Tjønneland
Anne
A
Overvad
Kim
K
Olsen
Jørgen H
JH
D000273:Adipose Tissue / Q000737:chemistry*; D001943:Breast Neoplasms / Q000453:epidemiology*; D016022:Case-Control Studies; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D006843:Hydrocarbons, Chlorinated / Q000032:analysis*; D016015:Logistic Models; D008875:Middle Aged; D010573:Pesticide Residues / Q000032:analysis; D011078:Polychlorinated Biphenyls / Q000032:analysis; D017698:Postmenopause; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires
D006843:Hydrocarbons, Chlorinated; D010573:Pesticide Residues; D011078:Polychlorinated Biphenyls