Environment and Breast Cancer: Science Review

Evidence From Humans
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Serum organochlorines and breast cancer: a case-control study among African-American women
Gatto, N. M., Longnecker, M. P., Press, M. F., Sullivan-Halley, J., McKean-Cowdin, R., Bernstein, L. Cancer Causes Control. 2007. 18:1, 29-39.
Topic area
Environmental pollutant - Organochlorines PCBs
Study design
Population-based case control
Funding agency
NCI NIEHS National Institute of Child Health and H
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Analyses stratified by menopausal status (data not shown)
Number of Controls
Controls: 327
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
355 African-American cases from the Los Angeles site of the CARE study. Cases in the CARE study were an age-stratified random sample of Caucasian and African American women (with oversampling of African American women) diagnosed with breast cancer at age 35-64 between 1994-1998, identified from a population-based county cancer registry. Cases had histologically confirmed invasive breast cancer and controls were identified through random digit dialing, frequency matched to age (within 5 years) and racial distribution of the cases. Those who did not provide blood samples were excluded.
Comment about participation selection
Among patients who were selected for participation, 15.5% of cases and 21.5% of controls refused to give blood samples and were excluded.
Exposure Investigated
Exposures investigated
Lipid-standardized serum measures from blood samples were collected at the time of enrollment (treatment status varied for cases) and analyzed for total PCBs in serum, based on a commercial mixtures Araclor 1242 and 1260.
Exposure assessment comment
145 cases (40.8%) and 138 controls (42.2%) had no detectable PCBs, which served as the study's reference group.
Breast cancer outcome investigated
Primary incident breast cancer
Ethnic groups with separate analysis
If this study provided a separate analysis by ethnic or racial group, the groups are listed here.
African American
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.
BMI, lifetime physical activity, breastfeeding, total number of full-term pregnancies, family history, education, and menopausal status
Strength of associations reported
Total PCBs (μg/g) (Ref=Q1):
2nd quintile OR 1.06 (95% CI 0.67-1.67)
3rd quintile OR 0.82 (95% CI 0.50-1.33)
4th quintile OR 0.76 (95% CI 0.47-1.24)
5th quintile OR 1.01 (95% CI 0.63-1.63)

DDE (ug/g) (Ref=Q1):
2nd quintile OR 0.98 (95% CI 0.59-1.62)
3rd quintile OR 1.07 (95% CI 0.65-1.75)
4th quintile OR 1.14 (95% CI 0.69-1.88)
5th quintile OR 1.02 (95% CI 0.61-1.72)

Among women who had not received chemotherapy, odds of breast cancer were significantly higher for women with total PCBs > 0.47 μg/g vs below the detection limit. p-interaction for treatment with chemotherapy = 0.08.
Results Comments
No significant associations were found between PCB levels and breast cancer risk, stratified by tumor receptor status, p53 overexpression, or HER2 status.
Author address
Department of Preventive Medicine, Keck School of Medicine of the University of Southern California, USC/Norris Comprehensive Center, 1441 Eastlake Avenue, Room 4449, Los Angeles, CA 90033, USA.
Reviewers Comments
This study notably focuses on African-American women, who are underrepresented in epidemiological literature on breast cancer and environmental pollutants.