Environment and Breast Cancer: Science Review
About
Physical activity and risk for breast cancer a prospective cohort study among Swedish twins
Moradi, T., Adami, H. O., Ekbom, A., Wedren, S., Terry, P., Floderus, B., Lichtenstein, P. International Journal of Cancer. 2002. 100:1, 76-81.
Topic area
Physical Activity - Body size
Physical Activity - Body size
Study design
Prospective cohort
Prospective cohort
Funding agency
Other: John D. and Catherine T. MacArthur Foundati
Other: John D. and Catherine T. MacArthur Foundati
Study Participants
Number of Cases
506
506
Menopausal Status
Post menopausal
The menopausal status of women included in this study is listed here.
Pre menopausalPost menopausal
Number in Cohort
Cohort: 9539
Cohort: 9539
Cohort participation rate
Retention/participation exceeded 70% for exposed a
Retention/participation exceeded 70% for exposed a
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: Swedish Twin Registry: same-sex twin pairs born between 1901 and 1925; age 42-70 years at entry; both individuals alive in 1959-1961 while registry was being established
Ex: women with a prevalent malignant tumor at baseline; died within 1 year after baseline; diagnosed with a malignant tumor within 1 year after baseline; women born before 1901
Comment about participation selection
Strengths: nationwide design; complete long-term follow-up; information was collected prior to breast cancer diagnosis; analyzed breast cancer risk by physical activity and BMI; stratified cohort by age (born between 1918-1925 or between 1901-1917) Limitations: anthropometric data self-reported; leisure-time and physical activity self-reported; age at menarche, age at menopause, and use of hormone replacement therapy data was not obtained from participants
Strengths: nationwide design; complete long-term follow-up; information was collected prior to breast cancer diagnosis; analyzed breast cancer risk by physical activity and BMI; stratified cohort by age (born between 1918-1925 or between 1901-1917) Limitations: anthropometric data self-reported; leisure-time and physical activity self-reported; age at menarche, age at menopause, and use of hormone replacement therapy data was not obtained from participants
Exposure Investigated
Exposures investigated
Sedentary lifestyle, BMI at 25 yrs, BMI at 40 yrs, BMI at age 42-70 and BMI at age 51-70
Sedentary lifestyle, BMI at 25 yrs, BMI at 40 yrs, BMI at age 42-70 and BMI at age 51-70
How exposure was measured
Questionnaire, self-administered
Questionnaire, self-administered
Exposure assessment comment
Physical activity and anthropometric data self-reported
Physical activity and anthropometric data self-reported
Breast cancer outcome investigated
Primary breast cancer
Primary breast cancer
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.
Adequately controlled, Confounders: place of residence during childhood/adolescence and adulthood, number of children, alcohol intake, smoking status, BMI in age-specific quartiles, and height
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: BMI Effect modifiers in body size analysis: physical activity Follow-up: 30 years
Effect modifiers: BMI Effect modifiers in body size analysis: physical activity Follow-up: 30 years
Strength of associations reported
Results include women from both birth cohorts:
Association between breast cancer risk and physical activity during leisure time, regular activity vs. sedentary, RR=0.8(0.6-1.2) trend p=0.3
Association between breast cancer risk and physical activity at work, strenuous vs. sedentary, RR=1.0(0.7-1.5) trend p=0.9
Association between breast cancer risk and physical activity during leisure time, regular activity vs. sedentary, in women with a high BMI at age 25, >23.3 vs. <20, RR=0.4(0.1-1.1) trend p=0.5
Association between breast cancer risk and physical activity during leisure time, regular activity vs. sedentary, in women with a high BMI at age 40, >25.1 vs. <21.3, RR=0.7(0.3-1.6) trend p=0.4
Association between breast cancer risk and physical activity during leisure time, regular activity vs. sedentary, in women with a high BMI at age 42-70, >26.4 vs. <22, RR=1.1(0.5-2.3) trend p=0.7
Results include women from both birth cohorts:
Association between breast cancer risk and physical activity during leisure time, regular activity vs. sedentary, RR=0.8(0.6-1.2) trend p=0.3
Association between breast cancer risk and physical activity at work, strenuous vs. sedentary, RR=1.0(0.7-1.5) trend p=0.9
Association between breast cancer risk and physical activity during leisure time, regular activity vs. sedentary, in women with a high BMI at age 25, >23.3 vs. <20, RR=0.4(0.1-1.1) trend p=0.5
Association between breast cancer risk and physical activity during leisure time, regular activity vs. sedentary, in women with a high BMI at age 40, >25.1 vs. <21.3, RR=0.7(0.3-1.6) trend p=0.4
Association between breast cancer risk and physical activity during leisure time, regular activity vs. sedentary, in women with a high BMI at age 42-70, >26.4 vs. <22, RR=1.1(0.5-2.3) trend p=0.7
Author address
Department of Medical Epidemiology, Karolinska Institutet, Stockholm, Sweden. Tahereh.Moradi@klinvet.ki.se
Department of Medical Epidemiology, Karolinska Institutet, Stockholm, Sweden. Tahereh.Moradi@klinvet.ki.se