Environment and Breast Cancer: Science Review

Evidence From Humans
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Breast cancer risk factors and age at diagnosis: an Icelandic cohort study
Tryggvadottir, L., Tulinius, H., Eyfjord, J. E., Sigurvinsson, T. International Journal of Cancer. 2002. 98:4, 604-8.
Topic area
Body size
Study design
Nested case-control
Funding agency
US Army Medical Research Acquisition Activity
Study Participants
Number of Cases
1,120 (invasive only)
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Number of Controls
Controls: 10,537
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: attended a nation-wide cervical and breast cancer screening program at the Cancer Detection Clinic (CDC) between 1979 and 1995; age 26-90 yrs at diagnosis with first invasive breast cancer (cases); were alive at least until the diagnosis-year of their matched case (controls)
Comment about participation selection
Strengths: answers given before diagnosis of invasive breast cancer; analyzed breast cancer risk and age at diagnosis by height and weight; cases and controls were matched on age and on birth year; large number of cases Limitations: anthropometric data self-reported, only height and weight were measured as exposures; does not stratify results by menopausal status
Exposure Investigated
Exposures investigated
Height and weight
How exposure was measured
Questionnaire, self-administered
Exposure assessment comment
Anthropometric data self-reported
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 menarche, lactation, height and weight
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
Effect modifiers: age at diagnosis
Strength of associations reported
Association between breast cancer risk and height, increments of 5 cm, OR=1.09(1.03-1.16) trend p=0.004
Association between breast cancer risk in women >55 years and height, increments of 5 cm, OR=1.12(1.03-1.22) trend p=0.011
Association between breast cancer risk and weight, increments of 10 kg, OR=1.03(0.97-1.09) trend p=0.275
Association between breast cancer risk in women >55 years and weight, increments of 10 kg, OR=1.07(0.99-1.16) trend p=0.078
Author address
Icelandic Cancer Registry, Icelandic Cancer Society, Reykjavik, Iceland. laufeyt@krabb.is