Environment and Breast Cancer: Science Review

Evidence From Humans
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Body size, physical activity, and breast cancer hormone receptor status: results from two case-control studies
Enger, S. M., Ross, R. K., Paganini-Hill, A., Carpenter, C. L., Bernstein, L. Cancer Epidemiology, Biomarkers & Prevention. 2000. 9:7, 681-7.
Topic area
Body size - Physical Activity
Study design
Population based case-control
Funding agency
NCI, NIH, Department of Health and Human Services
Study Participants
Number of Cases
1,184 (424 pre) (760 post) (invasive and in situ) (taken from two previous case-control studies)
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Number of Controls
Control: 1,805 (714 pre) (1,091 post) (taken from two previous case-control studies)
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: women under 40 years of age diagnosed with invasive or in situ breast cancer between 7/1/83 and 12/31/88 (cases); women ages 55 to 64 diagnosed with invasive or in situ breast cancer between 3/1/87 and 12/31/89 (cases); resident of Los Angeles County; white or Hispanic; born in the US, Canada or Western Europe Ex: cases who could not be matched with a control; women who were no longer menstruating (participants of premenopausal study); participants who had no information on family history of breast cancer; women who were premenopausal (participants of postmenopausal study); women who had an unknown age at menopause (postmenopausal study); women who did not provide complete information on education, alcohol consumption, pregnancies, breastfeeding, or weight
Comment about participation selection
Strengths: ER and PR status collected from participants; in-person interviews administered; physical activity information obtained; analyzed pre and post anthropometric variables with breast cancer risk according to joint ER/PR status; large case-control study; examined the interaction of BMI and physical activity among pre and post menopausal women with ER+/PR+ tumors; obtained BMI findings consistent with a prospective cohort of over 37,000 postmenopausal women Limitations: Anthropometric variables self-reported; many participants excluded from study; possibility that women with and without receptor status information have different risk factor profiles; possibility of recall bias from participants
Exposure Investigated
Exposures investigated
BMI, BMI at 18 years, % change of BMI from 18 years to reference date
How exposure was measured
Questionnaire, in person Anthropometric measurement, self-administered
Exposure assessment comment
Anthropometric 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.
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, socioeconomic status, number of full-term pregnancies, duration of breastfeeding, age at menopause, HRT use, family history of breast cancer, alcohol consumption, physical activity, and age at menarche
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: ER/PR status, menopausal status, physical activity ER+PR-, ER+PR+, ER-PR+
Strength of associations reported
Association between ER+/PR+ breast cancer and BMI, >27.1 vs <21.7, OR=2.45(1.73-3.47) trend p=0.0001
Inverse association between postmenopausal ER+/PR- breast cancer and physical activity, >17.6 hrs/wk vs 0 hrs/wk, OR=0.43(0.19-0.98) trend p=0.03
Inverse association between premenopausal ER-/PR- breast cancer and physical activity, >17.6 hrs/wk vs 0 hrs/wk, OR=0.46(0.24-0.92) trend p=0.02
Inverse association between postmenopausal ER+/PR+ breast cancer and women with a low BMI, low vs. high, and a high level of physcial activity, >17.6 hrs/wk vs 0 hrs/wk, OR=0.32(0.15-0.65) (Interaction)
Author address
Research and Evaluation Department, Kaiser Permanente Medical Care Program, Southern California, Pasadena 91188, USA. Shelley.M.Enger@kp.org