Environment and Breast Cancer: Science Review

Evidence From Humans
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Evidence of prenatal influences on breast cancer risk
Ekbom, A., Trichopoulos, D., Adami, H. O., Hsieh, C. C., Lan, S. J. Lancet. 1992. 340:8826, 1015-8.
Topic area
Early life exposures
Study design
Nested case-control
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Number of Controls
Controls: 1197
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
All women born at the University Hospital in Uppsala between 1874 and 1954 who survived at least until Jan 1, 1958. Eligible patients were all women in the National Cancer Registry (1958-87) and the regional cancer registries (1988-90) who had invasive breast cancer, controls were the offspring of the first three mothers who were administered to Uppsala Hospital after the case's mothers and who gave birth to at least one female baby. Ex: Each case who was one of twins, each control who had died, emigrated, or had breast cancer diagnosed before the corresponding case, and who were twins.
Comment about participation selection
Selection bias: took only women who delivered at the University Hospital, end of 19th century and begining of 20th century many women delivered at home.
Exposure Investigated
Exposures investigated
Birth weight, birth length, maternal age, maternal pre-eclampsia/eclampsia,
How exposure was measured
Medical record of mother's delivery
Exposure assessment comment
Diagnostic criteria and accuracy of medical records may have changed during the past century
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.
BMI, 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
Conditional logistic regression conditioned on age and birth date, and additionally adjusted for socioeconomic status, parity, maternal age at menarche, and other early life exposures. Adjusted RR with 95% CI, birth weight: >=4000g versus 2500-2999g, birt
Strength of associations reported
Birth weight: 1.23 (0.75 - 2.00), birth length 1.16 (0.81 -1.67); maternal age: 1.01 (0.92 -1.12); maternal pre-eclampsia/eclampsia: 0.24 (0.09 - 0.70)
Results Comments
The negative association of pre-eclampsia/eclampsia with breast cancer risk is strong and statistically significant. Birth weight and length don't show any individual association but both associations are in the predicted direction (positive).
Author address
Cancer Epidemiology Unit, Uppsala University Hospital, Sweden.