Environment and Breast Cancer: Science Review


Evidence From Humans
 
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Physical activity and breast cancer risk in the College Alumni Health Study (United States)
Sesso, H. D., Paffenbarger, R. S., Jr., Lee, I. M. Cancer Causes & Control. 1998. 9:4, 433-9.
Topic area
Physical Activity - Body size
Study design
Prospective cohort
Study Participants
Number of Cases
109 (28 pre) (81 post)
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Number in Cohort
Cohort: 1566
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: participants of the College Alumni Health Study: matriculated in an undergraduate or graduate program at the University of Pennsylvania between 1928 and 1940; returned a mailed questionnaire that was sent in 1962 Ex: history of breast cancer by 1962 (baseline); incomplete baseline data on physical activity, body weight, height and age
Comment about participation selection
Strengths: follow-up questionnaires sent in 1976, 1980 and 1993; lengthy follow-up of 31 years; analyzed breast cancer risk by physical activity and BMI; analyzed breast cancer risk by physical activity and menopausal status Limitations: all participants had a high level of education; anthropometric and physical activity data was self-reported; low participation rate (66%); measured physical activity at baseline, but not during follow-ups; limited number of cases, especially premenopausal cases; menopausal status was determined by a cut off at age 55
Exposure Investigated
How exposure was measured
Questionnaire, self-administered
Exposure assessment comment
Anthropometric data was self-reported
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: age, BMI, age at menarche, age at menopause, family history of breast cancer, HRT use and parity
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 and BMI For the body size analysis considered physical activity as an effect modifier. Follow-up: 31 years
Strength of associations reported
Association between breast cancer risk and physical activity, 1000+ kcal/wk vs. <500kcal/wk, in women with a BMI <22, RR=0.77(0.41-1.45) trend p=0.41
Association between breast cancer risk and physical activity, 1000+ kcal/wk vs. <500kcal/wk, in women with a BMI >22, RR=0.72(0.38-1.37) trend p=0.28
Inverse association between physical activity, >1000 kcal/wk vs. <500kcal/wk, in women over 55 years of age and breast cancer risk, RR=0.49(0.28-0.86) trend p=0.015
Association between breast cancer risk and physical activity, 1000+ kcal/wk vs. <500kcal/wk, RR=0.73(0.46-1.14) trend p=0.17
Association between physical activity, >1000 kcal/wk vs. <500kcal/wk, in women under 55 years of age and breast cancer risk, RR=1.83(0.77-4.31) trend p=0.014
Author address
Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA.