Environment and Breast Cancer: Science Review

Evidence From Humans
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Recent diet and breast cancer risk: the California Teachers Study (USA)
Horn-Ross, P. L., Hoggatt, K. J., West, D. W., Krone, M. R., Stewart, S. L., Anton, H., Bernstei, C. L., Deapen, D., Peel, D., Pinder, R., Reynolds, P., Ross, R. K., Wright, W., Ziogas, A. Cancer Causes Control. 2002. 13:5, 407-15.
Study design
Prospective cohort
Funding agency
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Post menopausal and premenopausal combined
Number in Cohort
Cohort: 111,526
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: Active and retired female teachers and administrators enrolled in 1995-1996 in the California State Teachers Retirement System; participants of the California Teacher Study (CTS) Ex: not residing in California at baseline, had joined the cohort after 1997, reported having been diagnosed with breast cancer prior to completing the baseline questionnaire, or were identified by the California cancer registry as having had a previous breast cancer, had not completed the dietary questionnaire, or whose self-report of food consumption was judge to be over reported or underreported. Women who developed in situ carcinoma of the breast during follow-up
Comment about participation selection
Large cohort, same education level
Exposure Investigated
Exposures investigated
Recent intake of beta-carotene, vitamin C and E Carbohydrate Phytoestrogens (Genistein; Secoisolariciresiniol, Daidzen) Total fat, saturated fat, polyunsaturated fat (linoleic acid); monounsaturated fat (oleic acid)
How exposure was measured
Questionnaire, self-administered, FFQ
Exposure assessment comment
All participants had low exposure to phytoestrogens
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.
Confounding was adequately controlled
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 RR with 95% CI, higher versus lower quintile of intake, interaction with BMI and menopausal status, effect modification by receptor status (for phytoestrogens), follow-up 2 years, latency period of one year
Strength of associations reported
β carotene 1.1 (0.9-1.4); vitamin C 1.1 (0.8-1.3); vitamin E 1.1 (0.9-1.4)
Carbohydrate: 0.8 (0.5-1.2)
Genistein RR: 1.0 (0.7-1.3); daidzein RR: 0.9 (0.7 - 1.2); secoisolariciresinol RR:1.4 (1.0-1.8)
Total fat: 0.8 (0.6-1.2); saturated fat: 0.8 (0.6-1.2); polyunsaturated: 0.9 (0.7-1.3); monounsaturated: 0.9 (0.6-1.2)
Results Comments
Recent consumption of anti-oxidant vitamins was not associated with breast cancer, nor were the associations modified by menopausal status. The effect of recent phytoestrogen consumption on breast cancer risk were equally null, no substantial differences in the effects of phytoestrogens by menopausal status or by the estrogen receptor. Carbohydrates were not related to risk of breast cancer, nor was the association modified by menopausal status. Recent consumption of the different subtypes of fat was not associated with breast cancer, nor were the associations modified by menopausal status.
Author address
Northern California Cancer Center, Union City 94587, USA. phornros@nccc.org