Environment and Breast Cancer: Science Review

Evidence From Humans
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Physical activity in usual occupation and risk of breast cancer (United States)
Coogan, P. F.,, Newcomb, P. A., Clapp, R. W.,, Trentham-Dietz, A.,, Baron, J. A.,, Longnecker, M. P. Cancer Causes and Control. 1997. 8, 626-631.
Topic area
Physical Activity - Body size
Study design
Population based case-control
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Number of Controls
Controls: 6783
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: residents of Maine, Wisconsin, Massachusetts and New Hampshire age 74 years or younger who reported a newly diagnosed cancer to the state cancer registry between 4/88 and 12/91 (cases); women with listed telephone numbers; women less than 65 years with a driver's license from one of the four states mentioned earlier (controls); women age 65-74 who were Medicare beneficiaries (controls) Ex: women with a prior history of breast cancer; women who were housewives, students, volunteers or who never worked owing to disability; women whose occupational physical activity could not be classified
Comment about participation selection
Strengths: Large population based case control; Interviewers were not aware of the subject's disease during the interview; analyzed breast cancer risk by four categories of occupational physical activity; stratified results by menopausal status, BMI and parity Limitations: Low participation rate; interviews were done over the telephone; occupational physical activity and anthropometric data were self-reported; did not examine lifetime history of physical activity; did not examine leisure activities
Exposure Investigated
Exposures investigated
Physical activity and BMI
How exposure was measured
Questionnaire, by telephone
Exposure assessment comment
Occupational physical activity and anthropometric data were self-reported
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: family history of breast cancer; alcohol consumption; BMI; menopausal status; education; history of benign breast disease; age at menarche; parity; age at first birth; level of physical activity during ages 14-22
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: BMI, parity and menopausal status
Strength of associations reported
Women with heavy-activity occupations had a lower risk of breast cancer than women with sedentary jobs, OR=0.74(0.57-0.96)
Women with medium-activity occupations with a BMI of 23.6 or less vs a BMI of more than 23.6 had a lower risk of breast cancer than women with sedentary jobs, OR=0.81(0.68-0.96)
Controls participation rate
Less than 70% (60%)