Environment and Breast Cancer: Science Review


Evidence From Humans
 
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Physical activity and breast cancer risk among Asian-American women in Los Angeles
Yang, D.,, Bernstein, L.,, Wu, A. H. Cancer. 2003. 97, 2565-2575.
Topic area
Physical Activity
Study design
Population based case-control
Funding agency
California Breast Cancer Research Program
Study Participants
Number of Cases
501 (206 pre) (278 post) (160 Chinese) (146 Japanese) (195 Filipino)
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Number of Controls
Controls: 594 (288 pre) (302 post) (228 Chinese) (175 Japanese) (191 Filipino)
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: Chinese, Japanese and Filipino women between the ages of 25 and 74 who were diagnosed with breast cancer between 1/1/95 and 12/31/97 (cases); women matched to cases by age, neighborhood and ethnicity (controls) Ex: women with incomplete interviews
Comment about participation selection
Strengths: population based study; one of the first studies to analyzed breast cancer risk in Asian and Asian-American; analyzed breast cancer risk in Asian and Asian-American women by lifetime recreational physical activity and occupational physical activity; assessed the intensity, duration and frequency of physical activity; used MET hrs/wk to quantify physical activity; conducted in person interviews; assessed total caloric intake Limitations: low response rates among cases and controls; did not assess household activity patterns
Exposure Investigated
Exposures investigated
Physical inactivity
How exposure was measured
Questionnaire, in person Anthropometric measurement, self-administered Other: Physical activity data, self-reported
Exposure assessment comment
Anthropometric and physical activity 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.
Chinese Japanese Filipino
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: education, migration history, parity, menopausal status, years with active job, job activity category, soy intake during adolescence and adult life
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 modifiers: menopausal status; caloric intake; BMI; migration status; ethnicity
Strength of associations reported
Inverse association between breast cancer risk and years of recreational physical activity, 30+ years vs. none, OR=0.48(0.27-0.87) trend p<0.001
Inverse association between breast cancer risk and average hours per week of recreational physical activity, 3.01+ hrs/week vs. none, OR=0.44(0.26-0.77) trend p<0.001
Inverse association between breast cancer risk and average MET hrs/wk of recreational physical activity, >12 hrs/wk vs. <3 hrs/wk, OR=0.47(0.28-0.80) trend p<0.001
Inverse association between breast cancer risk and average MET hrs/wk of recreational physical activity in Chinese women, >12 hrs/wk vs. <3 hrs/wk, OR=0.42(0.22-0.81) trend p=0.01
Inverse association between breast cancer risk and average MET hrs/wk of recreational physical activity in Filipino women, >12 hrs/wk vs. <3 hrs/wk, OR=0.47(0.24-0.90) trend p=0.002
Results Comments
No association between breast cancer risk and occupational physical activity, active blue collar job vs. sedentary job, OR-0.91(0.55-1.50) No association between breast cancer risk and average MET hrs/wk of recreational physical activity, >12 hrs/wk vs. <3 hrs/wk, amongst women with a high BMI, >24.6 vs. <21.5, OR=0.65(0.30-1.39) trend p=0.18