Environment and Breast Cancer: Science Review

Intrauterine environment and breast cancer risk in women: a population-based study
Ekbom, A., Hsieh, C. C., Lipworth, L., Adami, H. Q., Trichopoulos, D. J Natl Cancer Inst. 1997. 89:1, 71-6.

Topic area
Early life exposures
Early life exposures
Study design
Nested case-control
Nested case-control
Funding agency
NCI; CaP CURE Foundation
NCI; CaP CURE Foundation

Study Participants
Number of Cases
1068
1068
Number of Controls
Controls: 2727
Controls: 2727
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: women born at one of the five participating hospitals in the Uppsala-Orebro Health care region in Sweden during the period from 1874 through 1961 and who survived at least until January 1, 1958. Eligible cases were all women in the National Cancer registry (1958-1992) and the Uppsala Regional Cancer Registry (1993-1994) who have been diagnosed with invasive breast cancer and had a code for any of the four relevant counties. Eligible controls subjects, females born to the first three mothers who were admitted to the corresponding hospital after the case patient's mother.
Comment about participation selection
Very good tracing of the women. Adjustment for other early life exposures.
Very good tracing of the women. Adjustment for other early life exposures.

Exposure Investigated
Exposures investigated
Birth weight, birth length, maternal age, maternal pre-eclampsia/eclampsia, neonatal jaundice, severe prematurity, twin membership
Birth weight, birth length, maternal age, maternal pre-eclampsia/eclampsia, neonatal jaundice, severe prematurity, twin membership
How exposure was measured
Medical record
Medical record
Exposure assessment comment
Diagnostic criteria may have changed since 1974, accuracy of medical report
Diagnostic criteria may have changed since 1974, accuracy of medical report

Statistical Analysis
Breast cancer outcome investigated
Primary incident breast cancer
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.
No
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, race, parity, 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.
No
Description of major analysis
Conditional logistic regression model conditioned on age and birth date and additionally adjusted for maternal age, maternal socioeconomic status, maternal parity and other early life exposures. Adjusted OR with 95% CI; birth weight: >=4000g versus 2500-2
Conditional logistic regression model conditioned on age and birth date and additionally adjusted for maternal age, maternal socioeconomic status, maternal parity and other early life exposures. Adjusted OR with 95% CI; birth weight: >=4000g versus 2500-2
Strength of associations reported
Birth weight: 1.04 (0.77 -1.41); birth length: 1.05 (0.82 -1.34); maternal age: 1.06 (0.99 -1.14); pre-eclamsia/eclampsia: 0.41 (0.22 - 0.79); jaundice: 2.16 (1.27 - 3.67); prematurity: 3.96 (1.45 -10.81); twin:1.72 (0.92 - 3.20)
Birth weight: 1.04 (0.77 -1.41); birth length: 1.05 (0.82 -1.34); maternal age: 1.06 (0.99 -1.14); pre-eclamsia/eclampsia: 0.41 (0.22 - 0.79); jaundice: 2.16 (1.27 - 3.67); prematurity: 3.96 (1.45 -10.81); twin:1.72 (0.92 - 3.20)
Results Comments
Increasing breast cancer risk with birth size indicators remained weak , there is some evidence of an association with pregnancy estrogens and risk of breast cancer. Severe prematurity and neanatal jaundice were markedly and significantly associated with breast cancer risk.
Increasing breast cancer risk with birth size indicators remained weak , there is some evidence of an association with pregnancy estrogens and risk of breast cancer. Severe prematurity and neanatal jaundice were markedly and significantly associated with breast cancer risk.

Author address
Department of Cancer Epidemiology, Uppsala University, Sweden.
Department of Cancer Epidemiology, Uppsala University, Sweden.
Controls participation rate
More than 70 %
More than 70 %