Environment and Breast Cancer: Science Review

Evidence From Humans
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Birth weight and risk of breast cancer in a cohort of 106,504 women
Ahlgren, M., Sorensen, T., Wohlfahrt, J., Haflidadottir, A., Holst, C., Melbye, M. Int J Cancer. 2003. 107:6, 997-1000.
Topic area
Early life exposures
Study design
Retrospective cohort
Funding agency
Department of the US Army; Danish Cancer Society,
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Number in Cohort
Cohort: 106504
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: Girls born between 1930-1975 who attended school in Copenhagen, Denmark, Birth Order Study Database Ex: Women with recorded birth weight >=6000g or <=500g
Exposure Investigated
How exposure was measured
Other: School health records
Exposure assessment comment
Possible misclassification due to birthweight reported by parents at school
Statistical Analysis
Breast cancer outcome investigated
Primary incident breast cancer
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.
Body mass index, race, menopausal status, alcohol consumption, 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
Poisson regression model adjusted for age, calendar period. Additional adjustment for age at first birth and parity found no confounding effect. Adjusted RR with 95% CI, per 1000g increase in birth weight, interaction between age and birth weight trend,
Results Comments
The risk of breast cancer increases by 9% per 1000g increase in birth weight
Author address
Danish Epidemiology Science Centre, Department of Epidemiology Research, Statens Serum Institute, Artillerivej 5, DK-2300 Copenhagen S, Denmark.