Environment and Breast Cancer: Science Review

Evidence From Humans
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Risk factors, lifetime risk, and age at onset of breast cancer
Fraser, G. E., Shavlik, D. Annals of Epidemiology. 1997. 7:6, 375-82.
Topic area
Physical Activity - Body size
Study design
Prospective cohort
Study Participants
Number of Cases
218 (invasive only) (162 postmenopausal) (32 premenopausal) (24 unknown menopausal status)
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Number in Cohort
Cohort: 20,341
Cohort participation rate
Retention/participation exceeded 70% for exposed a
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: California non-Hispanic white women in the Adventist Health Study, Seventh-day Adventists, age at baseline 24-90 years, newly diagnosed with invasive breast cancer (cases) Ex: Women over the age of 90
Comment about participation selection
Strengths: analyzed energy and fat intake Limitations: Few confounders, only non-Hispanic white women in study, brief follow up, small cohort with few premenopausal cases, and anthropometric data self-reported
Exposure Investigated
How exposure was measured
Questionnaire, self-administered
Exposure assessment comment
Anthropometric data self-reported
Statistical Analysis
Ethnic groups with separate analysis
If this study provided a separate analysis by ethnic or racial group, the groups are listed here.
Nonhispanic Americans
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: parental history of cancer, family history of breast cancer, current HRT use, age at first full term pregnancy, BMI and physical activity
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
Follow up: 6 years
Strength of associations reported
Physical activity: low vs. higher level OR= 1.46 (1.11-1.92)
Association between breast cancer risk and BMI, above vs. below median of cohort, OR=1.32 (1.00-1.77)
Association between breast cancer risk and physical activity, low vs. higher level, OR=1.46 (1.11-1.92)
Results Comments
Physical inactivity had its most important effect on age at diagnosis. The effect was seemed to be more pronounced at younger ages Values of BMI above the mean tended to increase the risk of breast cancer but the association was not significant, RR=1.32(1.00-1.76)
Author address
Department of Epidemiology and Biostatistics, School of Public Health, Loma Linda University, CA 92350, USA.