Environment and Breast Cancer: Science Review

Evidence From Humans
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Serum vitamin E level and risk of female cancers
Knekt, P. Int J Epidemiol. 1988. 17:2, 281-6.
Study design
Nested Case-Control
Funding agency
Other: Cancer Society of Finland
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Post menopausal and premenopausal combined
Number in Cohort
Controls:123/ cohort:15,093
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: Women between the ages of 15-99, participating in the Finnish Social Insurance Institution’s Mobile Clinic Health Survey Ex: Participants of the study before the beginning of blood sampling (15 June 1968) and with a previous history of cancer
Comment about participation selection
Longitudinal study, Limited baseline characteristics
Exposure Investigated
Exposures investigated
Vitamin E (alpha-tocopherol)
Exposure assessment comment
One blood sample per participant, lack of accuracy of serum level of vitamin, length of storage of plasma sample: 11-17 years
Statistical Analysis
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.
Not considered: Menopausal status, alcohol, family history of breast cancer
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
Odds ratio, four highest quintiles of serum level versus lowest quintile, p - value, mean follow-up of 8 years
Strength of associations reported
OR= 1.03, p value >0.05
Results Comments
The analysis for all sites of hormone related cancers (breast, endometrium and ovary) showed a non-significant positive trend.
Author address
Research Institute for Social Security, Helsinki, Finland.