Environment and Breast Cancer: Science Review

Birth weight and breast cancer risk
Troisi, R., Hatch, E. E., Titus-Ernstoff, L., Palmer, J. R., Hyer, M., Strohsnitter, W. C., Robboy, S. J., Kaufman, R., Herbst, A., Adam, E., Hoover, R. N. Br J Cancer. 2006. 94:11, 1734-7.

Topic area
Early life exposures
Early life exposures
Study design
Prospective cohort study
Prospective cohort study
Funding agency
Not reported
Not reported

Study Participants
Number in Cohort
Cohort: 5847
Cohort: 5847
Cohort participation rate
More than 70% for the overall population, no detai
More than 70% for the overall population, no detai
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
DESAD
Dieckmann
WHS offspring
In: individuals with medical record documentation of DES exposure and a comparable cohort of unexposed women were the base population of the study. Eligible subjects of this study are women with birth weight data and who were free of breast cancer at the start of the follow-up.
Ex: prevalent breast cancer cases and women with no birth weight data at baseline
Comment about participation selection
The study cohort was organized initially for the study of DES exposure, therefore the study population may not be representative of the general population.
The study cohort was organized initially for the study of DES exposure, therefore the study population may not be representative of the general population.

Exposure Investigated
Exposures investigated
Birth weight, gestational age
Birth weight, gestational age
How exposure was measured
Medical records (80%) Other: Mother's report (20%)
Medical records (80%) Other: Mother's report (20%)
Exposure assessment comment
Data on gestational age and birth weight were derived from mothers' report among 20% of participants
Data on gestational age and birth weight were derived from mothers' report among 20% of participants

Statistical Analysis
Breast cancer outcome investigated
Primary invasive breast cancer
Primary invasive 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.
Age. Additional adjustment for calendar year, cohort, age, education, age at menarche, parity, menopausal status, height, body mass index, mother's smoking during pregnancy, DES exposure, and family history of breast cancer did not change effect estimates
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
Poisson regression was used to estimate age-adjusted incidence rate ratios. Potential confounding by other covariates were considered but not reported since the results did not change for more than 10% after additional adjustment. Potential effect modific
Poisson regression was used to estimate age-adjusted incidence rate ratios. Potential confounding by other covariates were considered but not reported since the results did not change for more than 10% after additional adjustment. Potential effect modific
Results Comments
Birth weight was likely to be related to breast cancer incidence among younger women and women with higher education. Gestational age was associated with breast cancer incidence.
Birth weight was likely to be related to breast cancer incidence among younger women and women with higher education. Gestational age was associated with breast cancer incidence.

Author address
Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, USA. troisir@mail.nih.gov
Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, USA. troisir@mail.nih.gov