Environment and Breast Cancer: Science Review

Evidence From Humans
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Dietary fiber, vitamins A, C, and E, and risk of breast cancer: a cohort study
Rohan, T. E., Howe, G. R., Friedenreich, C. M., Jain, M., Miller, A. B. Cancer Causes Control. 1993. 4:1, 29-37.
Study design
Nested case-control
Funding agency
Not reported
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; 1,182/ Cohort: 56,837
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: Participants of the Canadian National Breast Cancer Screening Study: Women aged 40 to 59, no history of breast cancer, not currently pregnant, had no mammogram in the preceding 12 months, histologically confirmed breast cancer for cases. Ex: Cases whose questionnaires were received after the diagnosis of breast cancer and any with inadequate dietary data
Exposure Investigated
Exposures investigated
Vitamins A,C, E, beta-carotene, alpha-tocopherol, fruits, vegetables
How exposure was measured
Questionnaire, self-administered, FFQ
Exposure assessment comment
Daily recommendation intake (DRI) of vitamin A in the lower quintile of intake (almost all participant are high consumers of Vit A)
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: BMI, race, parity, menopausal status other than surgical menopause
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
Adjusted OR with 95% CI; Vitamins A, C, E, beta-carotene, fruits, vegetables: higher versus lower quintile of intake; alpha-tocopherol: higher versus lower quartile of intake; effect modification with fiber intake, follow-up 6 years
Strength of associations reported
Vitamin A: 0.8 (0.55-1.17); β carotene 0.77 (0.53-1.10); vitamin C 0.88 (0.62-1.26); vitamin E 0.96 (0.63-1.45); fruits: 0.81 (0.57-1.14); vegetables: 0.86 (0.61-1.23)
Results Comments
Non-significant reduction in risk of breast cancer for vitamin A, vitamin C, and beta-carotene. There was no association between dietary vitamin-E intake and risk of breast cancer.
Author address
NCIC Epidemiology Unit, University of Toronto, Canada.