Environment and Breast Cancer: Science Review

Evidence From Humans
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Physical activity, body size, and estrogen metabolism in women
Matthews, C. E., Fowke, J. H., Dai, Q., Leon Bradlow, H., Jin, F., Shu, X. O., Gao, Y. T., Longcope, C., Hebert, J. R., Zheng, W. Cancer Causes & Control. 2004. 15:5, 473-81.
Topic area
Body size - Physical Activity
Study design
Other: Cross sectional analysis
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Number in Cohort
Cohort: 146
Cohort participation rate
Retention/participation exceeded 70% for exposed a
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Parent study: Shanghai Breast Cancer Study. North American Participants In: healthy, postmenopausal women who participated in a 9 week diet - estrogen metabolism study at the University of Massachusetts Memorial Health Center, over 45 years old, and received both a negative X-ray mammogram and a negative digital mammogram within a year of screening at the U of Mass Memorial Hospital Ex: previous cancer diagnosis, used cimetidine, tobacco, black cohosh, HRT, tamoxifen, meatonin, diuretics or alcohol in excess of two drinks per day, and women with liver, kidney, or adrenal ailments Chinese Participants In: age 25 to 64 at baseline, and resident of Shanghai Ex: prior cancer diagnosis
Comment about participation selection
Strengths: analyzed the effect of physical activity and body size in relation to the ratio of 2-hydroxyestrone (2HE) relative to 16alpha-hydroxyestrone (16HE) (increased oxidation of estrone to 2HE relative to 16HE has been hypothesized to reduce breast cancer risk), consistent results among the two very different study populations, anthropometric values were measured by trained staff Limitations: data is not directly comparable since it comes from two separate studies, and small sample size
Exposure Investigated
Exposures investigated
BMI, fat mass, body fat %, and W/H ratio
How exposure was measured
Questionnaire, self-administered in North American study Questionnaire, in person in Chinese study Anthropometric measurement, researcher-administered
Exposure assessment comment
Small sample size
Ethnic groups with separate analysis
If this study provided a separate analysis by ethnic or racial group, the groups are listed here.
North American Chinese
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:
Genetic characterization included
If the study analyzed relationships between environmental factors and inherited genetic variations, this field will be marked “Yes.” “No”, if not.
Results Comments
Women with low levels of leisure-time physical activity with higher BMIs had lower 2HE/16HE ratios than leaner women. Women with higher BMIs that were physically active had higher 2HE/16HE ratios. Physical activity has the potential to modify the advers effect of increased adiposity on estrogen metabolism in North American and Chinese women.
Author address
Vanderbilt-Ingram Cancer Center, Center for Health Services Research, Vanderbilt University Medical Center, Medical Center East, Suite 6100, Nashville, TN 37232-8300, USA. charles.matthews@vanderbilt.edu