Environment and Breast Cancer: Science Review


Evidence From Humans
 
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Effect of family history, obesity and exercise on breast cancer risk among postmenopausal women
Carpenter, C. L., Ross, R. K., Paganini-Hill, A., Bernstein, L. International Journal of Cancer. 2003. 106:1, 96-102.
Topic area
Body size - Physical Activity
Study design
Population based case-control
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Post menopausal
Number of Controls
Control: 1628
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: Group I: Diagnosed with breast cancer between 3/1/87 and 12/31/89; Caucasian (including Hispanic-Caucasian), born in the USA, Canada, or Western Europe; age 55-64 at diagnosis Group II: Diagnosed with breast cancer between 1/1/92 and 12/31/92; Caucasian (including Hispanic-Caucasian), or African American; born in the USA; age 55-69 years at diagnosis Group III: Diagnosed with breast cancer between 9/1/95 and 4/30/96; Caucasian (including Hispanic-Caucasian), or African American; born in the USA; age 55-72 years at diagnosis Ex: Women with unknown age at menopause; menstruating women; women with last menstrual period before the age of 35; women with missing covariate information or who did not know their first degree family history of breast cancer; controls with ages outside the age range of cases, <55 years or >72 years
Comment about participation selection
Strengths: Large population case-control study; evaluated lifetime exercise activity and obesity according to family history of breast cancer; interviews were in person, results are comparable to previous studies of both case-control and cohorts; reporting bias reduced due to systematic method of collecting information through the use of a life calendar Limitations: anthropometric data self-reported; large number of exclusions affected the case-control matching; possible that exercise history was systematically underreported or overreported by patients or controls; restricting the study to subjects with known age at menopause may have introduced a selection bias
Exposure Investigated
Exposures investigated
Physical inactivity, Height at 18 years, BMI at reference, BMI at 18 years, and change in weight from 18 years to reference date
How exposure was measured
Questionnaire, in person Anthropometric measurement, self-administered Other: physical activity, self-reported
Exposure assessment comment
Anthropometric and physical activity data 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: lifetime exercise activity, age at first full term pregnancy, age at menarche, age at menopause, BMI, family history of bc, interviewer, average MET hours per week of lifetime exercise activity, weight at reference date
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: family history of breast cancer
Strength of associations reported
Association between breast cancer risk and BMI at reference date, >27.1 vs. <21.7, OR=1.34(1.09-1.66) trend p=0.005
Association between breast cancer risk and BMI at reference date in women with a positive family history of breast cancer, >27.1 vs. <21.7, OR=2.90(1.86-4.54) trend p<0.0001
Association between breast cancer risk and BMI at reference date in women with no family history of breast cancer, >27.1 vs. <21.7, OR=1.20(0.97-2.19) trend p=0.08
No association between breast cancer risk and BMI at age 18 years, >22.17 vs. <18.9, OR=0.91(0.74-1.13) trend p=0.74
No association between breast cancer risk and Height at age 18 years, >66" vs. <62", OR=0.94(0.99-1.20) trend p=0.80
Inverse association between breast cancer risk and lifetime exercise between menarche and reference date (avg. MET hrs/wk), >17.6 vs. 0, OR=0.66(0.48-0.90) trend p=0.07
Inverse association between breast cancer risk and lifetime exercise between menarche and reference date in women without a family history of breast cancer (avg. MET hrs/wk), >17.6 vs. 0, OR=0.63(0.45-0.89) trend p=0.001
Author address
Department of Preventive Medicine, USC/Norris Comprehensive Cancer Center, Keck School of Medicine at the University of Southern California, Los Angeles, CA, USA. ccatheri@uci.edu