DDT (dicophane) and postmenopausal breast cancer in Europe: case-control study

Objective: To examine any possible links between exposure to DDE (1,1-dichloro-2,2-bis ( p -chlorophenyl)ethylene), the persistent metabolite of the pesticide dicophane (DDT), and breast cancer. Design: Multicentre study of exposure to DDE by measurement of adipose tissue aspirated from the buttocks. Laboratory measurements were conducted in a single laboratory. Additional data on risk factors for breast cancer were obtained by standard questionnaires. Setting: Centres in Germany, the Netherlands, Northern Ireland, Switzerland, and Spain. Subjects: 265 postmenopausal women with breast cancer and 341 controls matched for age and centre. Main outcome measure: Adipose DDE concentrations. Results: Women with breast cancer had adipose DDE concentrations 9.2% lower than control women. No increased risk of breast cancer was found at higher concentrations. The odds ratio of breast cancer, adjusted for age and centre, for the highest versus the lowest fourth of DDE distribution was 0.73 (95% confidence interval 0.44 to 1.21) and decreased to 0.48 (0.25 to 0.95; P for trend=0.02) after adjustment for body mass index, age at first birth, and current alcohol drinking. Adjustment for other risk factors did not materially affect these estimates. Conclusions: The lower DDE concentrations observed among the women with breast cancer may be secondary to disease inception. This study does not support the hypothesis that DDE increases risk of breast cancer in postmenopausal women in Europe. Key messages Organochlorines such as polychlorinated biphenyls and DDT may increase the risk of breast cancer in women DDE concentrations among the women with cancer were lower than among the controls, and there was an inverse risk gradient with higher DDE concentrations which remained significant after adjustment for risk factors for breast cancer These results are clearly incompatible with an increased risk of breast cancer at increased concentrations of DDE, although associations with other organochlorines cannot be excluded