Environment and Breast Cancer: Science Review

Evidence From Humans
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Dietary fat and the risk of breast cancer: a prospective study of 25,892 Norwegian women
Gaard, M., Tretli, S., Loken, E. B. Int J Cancer. 1995. 63:1, 13-7.
Study design
Prospective cohort
Funding agency
Other: Norwegian Cancer Society
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Post menopausal and pre menopausal combined
Number in Cohort
Cohort 24,897
Cohort participation rate
Greater than 70%
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: Women participating to the Norwegian National Health Screening Services (NHSS), living in one of the following counties: Finnmark, Sogn og Fjodane, and Oppland and were 35 to 49 years old at the time of the first screening (1977-1983) plus one random sample of women aged 20-34 at the time of the first screening and one second random sample of women aged 20-39 at the time of the second screening (1988) Ex: Pregnant women, women with primary amenorrhea and those who did not answer the question regarding menopausal status. Women who had at least 20 questions blank of the selected 31 questions about fat intake, women with caloric intake less than 2,100 kJ per day and women who had had any cancer diagnosed prior to the health screening and those who had any cancer diagnosed within the first year of follow-up.
Exposure Investigated
Exposures investigated
Total fat, saturated fat, monounsaturated fat, milk, whole milk
How exposure was measured
Questionnaire, self-administered, FFQ Questionnaire, in person
Exposure assessment comment
80 food items, questionnaire developed to determine risk factors of cardiovascular diseases
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: Family history of breast cancer, parity, alcohol consumption, race
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 (including adjustment for energy intake) with 95% CI, fat: higher versus lower quartile of intake, milk: highest versus lowest quintile of intake, subgroup for menopausal status, mean follow-up 10.4 years
Strength of associations reported
Total fat: 1.25 (0.86 - 1.81); saturated fat: 1.01 (0.75 - 1.57); monounsaturated fat: 1.72 (1.19 - 2.49), milk: 1.71 (0.86-3.38); whole milk: 2.91 (1.38-6.14)
Results Comments
Total fat intake was associated with elevated breast cancer risk for women in the highest quartile of intake, but the rate ratio was not significant after adjustment for total energy intake. Saturated fat consumption did not affect the risk of breast cancer. The most consistent finding was the positive association between women belonging to the highest quartile of monounsaturated fat intake and breast cancer risk.
Author address
Cancer Registry of Norway, Institute for Epidemiological Research, Montebello, Oslo.