Environment and Breast Cancer: Science Review

Evidence From Humans
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Plasma organochlorine levels and subsequent risk of breast cancer among Japanese women: a nested case-control study
Iwasaki, M., Inoue, M., Sasazuki, S., Kurahashi, N., Itoh, H., Usuda, M., Tsugane, S. Sci Total Environ. 2008. 402:2-3, 176-83.
Topic area
Environmental pollutant - Organochlorine pesticides DDT DDE
Study design
Nested case-control
Funding agency
Ministry of Health, Labour, and Welfare of Japan M
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Analyses stratified by menopausal status
Number of Controls
Controls: 278
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Women between 40-69 years of age were originally recruited into the Japan Public Health Center-based Prospective Study cohort between 1990 and 1993. Breast cancer cases identified from local hospitals and population cancer registries through 2002. Two controls were matched to each case on age (within 3 years), residential area, date of blood collection, time of day of blood collection, fasting time at blood collection, and menopausal status at blood collection.
Comment about participation selection
Authors note that 45% of women in the original cohort had blood samples drawn, so it is unclear if the cohort is representative of the general population.
Exposures investigated
Plasma p,p'-DDE, p,p'-DDT, hexachlorobenzene (HCB) and β-hexachlorocyclohexane (β-HCH) from blood collected at enrollment.
Breast cancer outcome investigated
Primary incident breast cancer
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.
Age at menarche, menopausal status at baseline, number of births, age at first birth, height, BMI, alcohol consumption.
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
Fourth quartile vs. first quartile:
p,p'-DDT: OR 0.99 (95% CI 0.47-2.08)
p,p'-DDE: OR 1.48 (95% CI 0.70-3.13)
HCB: OR 0.82 (95% CI 0.38-1.72)
β-HCH: OR 0.74 (95% CI 0.39-1.39)

Among premenopausal women, 4th quartile vs. 1st quartile:
p,p'-DDT: OR 2.45 (95% CI 0.70-8.63)
p,p'-DDE: OR 2.30 (95% CI 0.73-7.23)
HCB: OR 0.48 (95% CI 0.14-1.63)
β-HCH: OR 0.68 (95% CI 0.24-1.94)

Among postmenopausal women, 4th quartile vs. 1st quartile:
p,p'-DDT: OR 0.53 (95% CI 0.18-1.61)
p,p'-DDE: OR 1.07 (95% CI 0.31-3.63)
HCB: OR 1.09 (95% CI 0.33-3.54)
β-HCH: OR 0.51 (95% CI 0.19-1.38)
Results Comments
Authors say there was no significant positive association with lipid-standardized measures and do not show this data.
Author address
Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, 5-1-1 Tsukiji, Chuo-ku, Tokyo, 104-0045, Japan. moiwasak@ncc.go.jp
Reviewers Comments
The authors state that DDT was used in Japan until the early 1980s, meaning that some women in this cohort may have been exposed to DDT during childbearing age.