Evidence From Humans
 
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Relation between intensity of physical activity and breast cancer risk reduction
Friedenreich, C. M.,, Courneya, K. S.,, Bryant, H. E. Medicine & Science in Sports & Exercise. 2001. 33:9, 1538-1545.
Topic area
Physical Activity
Study design
Population based case-control
Funding agency
Other: Canadian Breast Cancer Research Initiative
Study Participants
Number of Cases
1,233 (462 pre) (771 post) (in situ and invasive only)
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Number of Controls
Controls: 1,237 (475 pre) (762 post)
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: women diagnosed with in situ and invasive breast cancer in Alberta, Canada between 8/95 and 8/97 (cases); resident of Alberta; younger than 80 years old; English speaking; completed interview; had a listed telephone number (controls) Ex:could not speak English; changed telephone numbers or had a disconnected telephone during the study; had incomplete interviews; diagnosed with a prior cancer; had many missing values
Comment about participation selection
Strengths: large population based case control study; cases were histologically confirmed; conducted in-person interviews; assessed diet; anthropometric data was measured by trained staff; assessed occupational, household and recreational activity using MET (ratio of the associated metabolic rate for a specific activity compared to the resting metabolic rate); compared controls to a sample of Albertans to address the issue of selection bias due to a low participation rate from controls; analyzed breast cancer risk by different types of physical activity stratified by menopausal status; one of the first studies to report effect modification on physical activity with breast cancer risk by menopausal status; assigned MET hours of physical activity per respondents data by using a copendium of physical activity Limitations: possible selection bias due to a low participation rate amongst controls
Exposures investigated
Physical activity
How exposure was measured
Questionnaire, in person
Ethnic groups with separate analysis
If this study provided a separate analysis by ethnic or racial group, the groups are listed here.
No
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.
Age, WHR, education, HRT use, history of benign breast disease, family history of breast cancer, alcohol consumption, smoking status
Genetic characterization included
If the study analyzed relationships between environmental factors and inherited genetic variations, this field will be marked “Yes.” “No”, if not.
No
Description of major analysis
Effect modification: menopausal status
Strength of associations reported
Inverse association between postmenopausal breast cancer and physical activity in women with a lifetime total activity of 42.7 or more hours/wk/yr OR=0.69(0.51-0.93) compared to women with a lifetime activity level of less than 28.8 hours/wk/yr. trend p=0.006
Inverse association between postmenopausal breast cancer and physical activity in women with a lifetime total household activity of 21.3 or more hours/wk/yr OR=0.69(0.49-0.96) compated to women with a lifetime total household activity of less than 8.8 hours/wk/yr. trend p=0.01
Inverse association between postmenopausal breast cancer and physical activity in women with a lifetime total of 22.2 or more hours/wk/yr of assigned moderate intensity (>3 to<6 METs) physical activity OR=0.59(0.42-0.83) compared to women with a lifetime total of less than 8.8 hours/wk/yr of assigned moderate intensity physical activity. trend p=0.002
Inverse association between postmenopausal breast cancer and physical activity in women with a lifetime total of 17.4 or more hours/wk/yr of self-reported moderate intensity physical activity OR=0.61(0.43-0.86) compared to women with a lifetime total of less than 4.9 hours/wk/yr of self-reported moderate intensity physical activitytrend p=0.01
Controls participation rate
Less than 70% (56.5%) but rate excludes deaths, lo
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