Environment and Breast Cancer: Science Review

Evidence From Humans
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Organochlorine insecticides DDT and chlordane in relation to survival following breast cancer
Parada, H., Jr., Wolff, M. S., Engel, L. S., White, A. J., Eng, S. M., Cleveland, R. J., Khankari, N. K., Teitelbaum, S. L., Neugut, A. I., Gammon, M. D. Int J Cancer. 2016. .
Topic area
Environmental pollutant - DDT Organochlorine pesticides
Study design
Population based case survival study
Funding agency
NCI NIEHS Babylon Breast Cancer Coalition
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
No analyses based on menopausal status
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Women in this survival study were residents of Nassau and Suffolk counties originally recruited for the Long Island Breast Cancer Study Project when they were diagnosed with invasive breast cancer in 1996-1997. Cases were recruited through regional pathology laboratories, and breast cancer mortality determined from National Death Index through 2011.
Comment about participation selection
In the LIBCSP, giving a blood sample was positively associated with being white, ever using alcohol, ever using HRT, ever having a mammography, and lactation history. Older women and former smokers were less likely to give blood. Blood donation was not associated with case-control status, so these differences between the total study popuvlation and the sub-population who donated blood should not bias the findings, but could affect generalizability. All cases with measures of DDT, DDE and chlordane in blood were included. About a half of the women were between the ages of 14 and 25 during the years of peak DDT use in the US, and about a third of the women may have been exposed to DDT in utero.
Exposures investigated
Lipid-standardized serum p,p'-DDE, p,p'-DDT and chlordane (sum of oxychlordane and trans-nonachlor). Samples collected an average of 3 months after diagnosis for cases (77% before chemotherapy initiation).
Confounders considered
Other breast cancer risk factors, such as family history, age at first birth, and hormone replacement therapy use, that were taken into account in the study.
Based on causal diagram: Age at diagnosis, smoking status, income, BMI, and parity/lactation.
Genetic characterization included
If the study analyzed relationships between environmental factors and inherited genetic variations, this field will be marked “Yes.” “No”, if not.
Strength of associations reported
5-year breast cancer mortality:
p,p'-DDT, 2rd tertile vs. 1st tertile: OR 2.94 (95% CI 1.12-7.67)
p,p'-DDT, 3rd tertile vs. 1st tertile: OR 2.72 (95% CI 1.04-7.13)
p,p'-DDE, 2nd tertile vs. 1st tertile: OR 1.10 (95% CI 0.48-2.52)
p,p'-DDE, 3rd tertile vs. 1st tertile: OR 0.85 (95% CI 0.32-2.23)
chlordane, 2nd tertile vs. 1st tertile: OR1.53 (95% CI 0.63-3.69)
chlordane, 3rd tertile vs. 1st tertile: OR 1.68 (95% CI 0.65-4.35)

15-year breast cancer mortality:
p,p'-DDT, 2rd tertile vs. 1st tertile: OR 1.59 (95% CI 0.90-2.83)
p,p'-DDT, 3rd tertile vs. 1st tertile: OR 1.23 (95% CI 0.68-2.24)
p,p'-DDE, 2nd tertile vs. 1st tertile: OR 0.92 (95% CI 0.53-1.62)
p,p'-DDE, 3rd tertile vs. 1st tertile: OR 0.70 (95% CI 0.36-1.37)
chlordane, 2nd tertile vs. 1st tertile: OR1.47 (95% CI 0.81-2.67)
chlordane, 3rd tertile vs. 1st tertile: OR 1.45 (95% CI 0.76-2.75)
Results Comments
Results were similar when analysis was restricted to postmenopausal cases, though the effect estimate for 5-year mortality and T3 vs T1 p,p'-DDT was somewhat higher (OR 3.90 (1.08-14.10)). For 5-year mortality, trend across increasing tertiles was significant for p,p'-DDT (p < 0.02).
Author address
Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC. Department of Preventive Medicine, Mt. Sinai School of Medicine, New York, NY. Department of Epidemiology, Columbia University, New York, NY. Department of Medicine,
Reviewers Comments
The authors note that (1) the higher risk of death within 5 years may reflect deaths among more susceptible women and (2) early life exposures could influence the aggressiveness and treatability of cancer later in life.