Environment and Breast Cancer: Science Review

Evidence From Humans
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The effect of physical activity on breast cancer risk: a cohort study of 30,548 women
Luoto, R.,, Latikka, P.,, Pukkala, E.,, Hakulinen, T.,, Vikho, V. European Journal of Epidemiology. 2001. 16:10, 973-980.
Topic area
Physical Activity - Body size
Study design
Prospective cohort
Funding agency
Not reported
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Number in Cohort
Cohort: 30,548
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: Finnish women who responded to a random sample sent annually from 1978-1993 (excluding 1985) age 15-64 years, participating in the Finnish adult health behavior survey Ex: women with missing data; women who were not able to be physically active due to disabilities
Comment about participation selection
Strengths: fairly large prospective cohort study; obtained confirmation of cases through a computerized record linkage system that is highly accurate; analyzed breast cancer risk by physical activity during leisure time and during the commute to work; stratified results by BMI and age Limitations: self-reported physical activity and anthropometric data; did not assess life long physical activity; did not assess occupational or household activity
Exposure Investigated
Exposures investigated
Sedentary lifestyle, BMI
How exposure was measured
Questionnaire, self-administered
Exposure assessment comment
Self-reported physical activity and anthropometric data
Statistical Analysis
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.
Confounders: age, BMI, education, length of follow-up, parity, age at first birth
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 and age Follow-up: 17 years
Strength of associations reported
No association between breast cancer risk and physical activity at leisure, daily vs. < once/week, RR=1.01(0.72-1.42) trend p=0.50
No association between breast cancer risk and physical activity at when commuting to work, > 30 min/day vs. unemployed/work at home, RR=0.87(0.62-1.24) trend p=0.83
Results Comments
No effect modification by BMI or age