Environment and Breast Cancer: Science Review

Evidence From Humans
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Association of body mass index, physical activity, and reproductive histories with breast cancer: a case-control study in Gifu, Japan
Hu, Y. H., Nagata, C., Shimizu, H., Kaneda, N., Kashiki, Y. Breast Cancer Research & Treatment. 1997. 43:1, 65-72.
Topic area
Body size - Physical Activity
Study design
Population based case-control (not clear that hospital covers all the population)
Funding agency
Not reported
Study Participants
Number of Cases
157 (87 premenopausal) (67 postmenopausal)
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Number of Controls
Control: 369 (202 premenopausal) (159 postmenopausal)
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: women diagnosed with breast cancer in Gihoku General Hospital between 7/1/89 and 7/30/93 (cases), age 26-75 years at baseline, women who attended a mass screening for breast cancer at Gihoku General and residents of Gifu, Japan Ex: women who died before they could respond to the questionnaire, women with breast diseases or hormone-related cancers and women who had no matched controls (3)
Comment about participation selection
Strengths: Analyzes a Japanese population whose age-adjusted incidence rate of breast cancer has been on the rise, first study to report that low BMI was independently associated with the risk of premenopausal breast cancer in Japan, and assessed physical activity in teenage years and twenties Limitations: does not adjust for any dietary differences, possible bias that stems from women who attend screening being more health conscious, anthropometric data self-reported, low participation rate, small study and mail survey might have limited the ability to collect data
Exposure Investigated
Exposures investigated
BMI, height at 12 years, weight at 12 years, height, total energy expenditure in teenage years and weight
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.
Japanese Women
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 at menarche, BMI, age at first birth, number of births, and duration of breast feeding
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
Association between breast cancer risk and height, >156 cm vs. <150 cm, RR=1.39(0.85-2.23) trend p=0.169
Association between breast cancer risk and weight, >56 kg vs. <49 kg, RR=0.85(0.53-1.35) trend p=0.485
Association between premenopausal breast cancer risk and BMI, 23+ vs. <21, RR=0.45(0.22-0.92)
Association between postmenopausal breast cancer risk and BMI, 24+ vs. <21.4, RR=1.98(0.86-4.55)
Association between premenopausal breast cancer risk and total energy expenditure in teenage years, 1100+(kcal/wk) vs. none, RR=0.72(0.38-1.38) trend p=0.294
Association between postmenopausal breast cancer risk and total energy expenditure in teenage years, 700+(kcal/wk) vs. none, RR=1.39(0.61-3.13) trend p=0.338
Results Comments
No association with relative height at age 12 or relative weight at age 12. Low risks were observed in premenopausal women with middle and high total energy expenditure in physical activity in teenage years compared to those with no physical activity, although these findings were not statistically significant No significant impact of BMI on risk of postmenopausal women: 23+ vs. <21, OR=1.24, 95% CI=0.63-2.45 Univariate analysis, all subjects, no association with relative height or relative weight at age 12, or recent adult height or weight.
Author address
Department of Public Health, Gifu University School of Medicine, Japan.
Controls participation rate
Greater than 70% (75.5%)