Environment and Breast Cancer: Science Review

Evidence From Humans
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Hormonal factors and breast tumor proliferation: do factors that affect cancer risk also affect tumor growth?
Oestreicher, N., White, E., Malone, K. E., Porter, P. L. Breast Cancer Research & Treatment. 2004. 85:2, 133-42.
Topic area
Body size
Study design
Cohort study
Study Participants
Number of Cases
484 (invasive only) (45 premenopausal) (436 peri/postmenopausal)
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: Women enrolled in the Breast Cancer Screening Program (BCSP), age 40 or older at baseline, underwent at least one screening mammogram between 1/1/88 and 12/31/93, diagnosed with a first primary invasive breast cancer within 24 months following their index mammogram between 1988 and 1995, and a resident of western Washington State Ex: Women with a history of breast cancer, women enrolled in BCSP for at least 24 months following their index mammogram and was not diagnosed with breast cancer and women who had died from any cause during the 24-month period subsequent to the index mammogram
Comment about participation selection
Strengths: cancers are assessed by stage, tumor size and tumor histology; one of the first studies to investigate the effect of BMI and body weight on tumor proliferation as measured by Ki-67(a protein that is present in the nucleus of cells only during the G1, S, G2 and M phase of cell cycles but not during the resting (G0) stage), computerized pharmacy database was used to determine hormone use, study used a screened population and study assessed two tumor proliferation measures, analyzed the effect of BMI and body weight on tumor proliferation through mitotic count Limitations: anthropometric data self-reported, few premenopausal women in study, study was restricted to women 40 years or older, utilized only two available measures of tumor cell proliferation, results were inconsistent among the two available measures of tumor cell proliferation, and height not examined as an exposure
Exposure Investigated
Exposures investigated
Weight and BMI
How exposure was measured
Questionnaire, self-administered
Exposure assessment comment
Anthropometric data self-reported
Breast cancer outcome investigated
Breast cancer recurrence or progression
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 at diagnosis and menopausal status
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
Higher body weight and BMI were associated with more Ki-67 protein in cells, but not with a higher mitotic count.
Author address
Fred Hutchinson Cancer Research Center, University of Washington, Seattle, WA, USA. ninao@u.washington.edu