Environment and Breast Cancer: Science Review


Evidence From Humans
 
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A prospective study of breast cancer risk using routine mammographic breast density measurements
Vacek, P. M., Geller, B. M. Cancer Epidemiology, Biomarkers & Prevention. 2004. 13:5, 715-22.
Topic area
Body size
Study design
Prospective cohort
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Number in Cohort
Cohort: 61,844 (39.2% pre) (60.8% post)
Cohort participation rate
Retention/participation exceeded 70% for exposed a
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: women with no prior history of breast cancer; had at least one mammogram with a breast density assessment in Vermont between April 1, 1996 and December 31, 2000 Ex: prior history of breast cancer; prior malignant biopsy; refused participation; women with less than 1 year of follow-up; women who did not have an exit mammogram before July 1, 2001 or a biopsy before July 1, 2002; women diagnosed with breast cancer within a year of the entry date
Comment about participation selection
Strengths: prospective study with a large number of cases; 192,343 person years of follow-up; analyzed breast cancer risk by breast density stratified by menopausal status and HRT use; analyzed breast cancer risk by BMI stratified by menopausal status and HRT use Limitations: anthropometric data were self reported; low participation rate due to many exclusions (66%); short duration of follow up; did not obtain information on menarche; different study populations and study designs might have affected results
Exposure Investigated
Exposures investigated
BMI and breast density
How exposure was measured
Questionnaire, self-administered
Exposure assessment comment
Anthropometric data were 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, family history of breast cancer; nulliparity; age at first childbirth, HRT use
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 HRT use Follow-up: 3.1 years (mean)
Strength of associations reported
Association between premenopausal breast cancer risk and BMI, (>30 vs <22), RR=0.85(0.61-1.20)
Association between postmenopausal breast cancer risk and BMI, (>30 vs <22), RR= 1.54(1.23-1.93)
Association between postmenopausal breast cancer risk and BMI in women who do not use HRT (>30 vs <22), RR=1.67(1.22-2.31)
Association between postmenopausal breast cancer risk and BMI in women who do use HRT (>30 vs <22), RR=1.30(0.90-1.88)
Association between breast cancer and breast density, extremely dense vs. entirely fat, RR=4.02(1.62-2.97)
Association between premenopausal breast cancer and breast density, extremely dense vs. entirely fat, RR=4.61(1.68-12.64)
Association between postmenopausal breast cancer and breast density, extremely dense vs. entirely fat, RR=3.88(2.60-5.78)
Author address
Department of Medical Biostatistics, University of Vermont College of Medicine, Vermont Cancer Center, Burlington, VT 05405, USA. pvacek@uvm.edu