Environment and Breast Cancer: Science Review

Evidence From Humans
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Lifetime physical activity and breast cancer risk in pre- and postmenopausal women
Dorn, J.,, Vena, J.,, Brasure, J.,, Freudenheim, J.,, Graham, S. Medicine & Science in Sports & Exercise. 2003. 35, 278-285.
Topic area
Physical Activity
Study design
Population based case-control
Funding agency
Not reported
Study Participants
Number of Cases
740 (301 pre) (439 post)
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Number of Controls
Control: 810 (316 pre) (494 post)
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: age 40-85 at enrollment; women diagnosed with breast cancer between 1986 and 1991 in 12 hospitals in western New York counties, Erie and Niagara (cases); owned a New York drivers' license (controls younger than 65 years); in Health Care Finance Administration records from the state of New York (controls older than 65 years)
Comment about participation selection
Strengths: large population based case-control study; analyzed breast cancer by physical activity measured at different time periods stratified by menopausal status; cases were histologically confirmed; conducted in-person interviews; analyzed breast cancer risk by occupational physical activity and by walking Limitations: low participation rate of cases and controls; self-reported recreational physical activity values; used job classifications to measure occupational physical activity; overall amount of strenuous activity reported by participants was modest
Exposure Investigated
Exposures investigated
Physical inactivity
How exposure was measured
Questionnaire, in person
Exposure assessment comment
Self-reported recreational physical activity values and used job classifications to measure occupational physical activity
Statistical Analysis
Ethnic groups with separate analysis
If this study provided a separate analysis by ethnic or racial group, the groups are listed here.
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.
Adequately controlled, confounders: age, education, age of menarche, family history of breast cancer, benign breast disease, BMI age at first pregnancy
Genetic characterization included
If the study analyzed relationships between environmental factors and inherited genetic variations, this field will be marked “Yes.” “No”, if not.
Description of major analysis
Effect modifiers: menopausal status
Strength of associations reported
Inverse association between postmenopausal breast cancer risk and physical activity 20 years before enrollment, 182+ hr/yr vs. 0 hr/yr, OR=0.51(0.31-0.83) trend p=0.27
Inverse association between premenopausal breast cancer risk and physical activity at age 16 years, 182+ hr/yr vs. 0 hr/yr, OR=0.61(0.40-0.94) trend p=0.11
Results Comments
No association between breast cancer risk and occupational physical activity
Controls participation rate
Less than 70% (50%)