Environment and Breast Cancer: Science Review

Evidence From Humans
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Adipose levels of polybrominated diphenyl ethers and risk of breast cancer
Hurley, S., Reynolds, P., Goldberg, D., Nelson, D. O., Jeffrey, S. S., Petreas, M. Breast Cancer Res Treat. 2011. 129:2, 505-11.
Topic area
Environmental pollutant - PBDEs Flame retardants
Study design
Hospital-based case control
Funding agency
CBCRP US Army Medical Research and Materiel Comman
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
No analyses based on menopausal status
Number of Controls
Controls: 56
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Participants were recruited from breast biopsy patients at two hospitals in the San Francisco Bay area of California between 1995-1998. Cases were women with histologically confirmed invasive breast cancer; controls were women with benign histological changes. Individuals were excluded if they were diagnosed with atypical hyperplasia or breast carcinoma in situ, had previously been diagnosed with cancer, or had previously been treated with radiation or Tamoxifen.
Comment about participation selection
Authors attempted but were not able to age-match cases and controls during recruitment. Controls were significantly younger than cases, which could result in downward bias as authors cite evidence that PBDE levels are inversely associated with age, whereas breast cancer risk increases with age.
Exposure Investigated
Exposures investigated
Breast adipose levels of polybrominated diphenyl ether (PBDE) flame retardants1995-1998 collected during diagnostic biopsy or surgical treatment.
Exposure assessment comment
Breast adipose tissue samples were taken at the time of surgical breast biopsy, local excision, or mastectomy.
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 and race
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
PBDEs Tertile 3 vs Tertile 1 (ng/g lipid):
BDE-47 (≥47.5 vs. ≤16.3): OR 0.56 (95% CI 0.19-1.68)
BDE-99 (≥15.8 vs. ≤9.7): OR 1.19 (95% CI 0.35-4.10)
BDE-100 (≥7.4 vs. ≤3.0): OR 0.91 (95% CI 0.33-2.53)
BDE-153 (≥13.1 vs. ≤4.2): OR 0.52 (95% CI 0.19-1.39)
BDE-154 (≥2.1 vs. ≤0.5): OR 1.67 (95% CI 0.44-6.29)
Total BDE (≥97.4 vs. ≤50.9): OR 2.04 (95% CI 0.45-9.20)
Author address
Cancer Prevention Institute of California, 2001 Center Street, Berkeley, CA, 94704, USA. susan.hurley@cpic.org
Reviewers Comments
The authors note that the control group may have included individuals whose benign breast conditions are on the causal pathway between exposure and development of breast cancer. This could bias estimates toward the null. Even if the benign breast changes are not on the causal pathway, if they are associated with exposure to PBDEs, estimates for breast cancer ORs would be biased downward. This is one of the few studies that examines PBDEs and breast cancer risk.