Environment and Breast Cancer: Science Review

Evidence From Humans
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The effect of atmospheric particulate matter on survival of breast cancer among US females
Hu, H., Dailey, A. B., Kan, H., Xu, X. Breast Cancer Res Treat. 2013. 139:1, 217-26.
Topic area
Environmental pollutant - Air pollution
Study design
Funding agency
Not reported
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
No analyses based on menopausal status
Cohort participation rate
N/A, this is a records-based study
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Female breast cancer cases diagnosed between 1999-2009 in all California counties in the Surveillance Epidemiology and End Results (SEER) database.
Comment about participation selection
17,446 women were excluded due to incomplete PM data.
Exposure Investigated
Exposures investigated
1999 particulate matter (PM) data, PM 10 and PM 2.5, from county-level daily monitoring in California.
How exposure was measured
Environmental sample Geographic location
Exposure assessment comment
PM includes small particles that may contain acids, organic chemicals, metals, or soil, and they may also act as a proxy for presence of other air pollutants.
Ethnic groups with separate analysis
If this study provided a separate analysis by ethnic or racial group, the groups are listed here.
White (32.72%), Black (30.85%), Others (38.22%)
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.
Individual level: age, cancer stage, race, marital status, year of diagnosis County level: education, income, accessibility to medical resources
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
Per 10 ug/m3 increase in PM10:
Among all women with breast cancer: HR 1.13 (95% CI 1.02-1.25)
Among black women with breast cancer, compared to white women with breast cancer: HR 1.61 (95% CI 1.52-1.70)

Per 5 ug/m3 increase in PM2.5:
Among all women with breast cancer: HR 1.86 (95% CI 1.12-3.10)
Among black women with breast cancer, compared to white women with breast cancer: HR 1.59 (95% CI 1.50-1.68)
Results Comments
At higher PM levels, women with in situ breast cancer had higher mortality than women with localized, regional, or distant breast cancer. Authors note this could reflect more common use of radiation treatment for early stage cancers, which could modify an association between air pollution and breast cancer.
Author address
Department of Epidemiology, College of Public Health and Health Professions and College of Medicine, University of Florida, P.O. Box 100231, Gainesville, FL 32610, USA.
Reviewers Comments
SEER does not provide individual level data that may alter breast cancer risk.