Environment and Breast Cancer: Science Review

Evidence From Humans
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Role of xenoestrogens and endogenous sources of estrogens on the occurrence of premenopausal breast cancer in Iran
Bidgoli, S. A., Eftekhari, T., Sadeghipour, R. Asian Pac J Cancer Prev. 2011. 12:9, 2425-30.
Topic area
Environmental pollutant - PAHs Dioxins
Study design
Population-based case-control
Funding agency
Not reported
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Analysis restricted to premenopausal status
Number of Controls
Controls: 100
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
The study population included individuals living in Tehran during 2009-2010. Cases were identified from self-reports registration and pathological reports. Cases and controls were excluded if there was evidence for menopause, pregnancy, or recent lactation; missing evidence on menstruation history; or if they were still menstruating by using exogenous hormones. Women were considered postmenopausal if they had undergone a bilateral ovariectomy or if their menses had stopped 12 months or more ago, unless due to hysterectomy. Controls were matched to cases by age (+/-5 years) and hospital records.
Comment about participation selection
The authors indicated that controls were matched to cases by hospital records, but did not further specify how controls were recruited. When controls are selected from hospitals, it is possible that these individuals were at the hospital for reasons that could be related to important risk factors associated with breast cancer.
Exposures investigated
Proximity of residence at interview to factories releasing PAHs and dioxin. AhR expression was measured in breast tissue of cases.
How exposure was measured
Geographic/GIS Questionnaire, self-administered
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.
Authors report that questionnaires asked about reproductive factors, family history of breast cancer, and BMI, but do not specify whether analyses were adjusted for these variables.
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
Residence < 4 km from PAH and dioxin-emitting factories: OR 4.80, p=0.001
Results Comments
While working addresses were obtained through exposure questionnaires, no separate analyses were performed for occupational proximity to factories.
Author address
Toxicogenomics Lab, Faculty of Pharmacy, Islamic Azad University, Tehran, Iran. arbabi.s@iaups.ac.ir