Environment and Breast Cancer: Science Review

Evidence From Humans
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Twin membership and breast cancer risk
Hsieh, C. C., Lan, S. J., Ekbom, A., Petridou, E., Adami, H. O., Trichopoulos, D. Am J Epidemiol. 1992. 136:11, 1321-6.
Topic area
Early life exposures
Study design
Hospital based case-control
Study Participants
Number of Cases
870 (17 twins)
Menopausal Status
The menopausal status of women included in this study is listed here.
Number of Controls
Controls: 2641(33 twins)
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Inclusion in already established case control breast cancer study in which singleton/multiple birth status was assessed In:Cases: female residents of Glamorgan, Wales or Boston, Massachussetts, who were hospitalized for a first diagnosis of breast cancer during the study period In: controls: females patients in beds closest to the index case, who were residents of the study area, who had never had breast cancer, and who were older than 35 years of age (except when the index case was younger than 35, in which instance the controls were age-matched within a range of 2 years) Ex: interview judged unreliable or when information on potential confoundings was not available.
Comment about participation selection
Multicentric study, controls are hospitalized patients with potential similar risk factors
Exposure Investigated
How exposure was measured
Questionnaire, in person
Exposure assessment comment
Few twin cases, especially in subgroups
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.
Race, family history of breast cancer, alcohol consumption
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
Multiple logistic regression adjusted for study center, age at interview, parity, age at first birth, age at menarche, height, BMI, maternal age at birth. Adjusted OR with 95% CI, twin versus sinleton birth, subgroups for twin with twin sister or twin bro
Strength of associations reported
All women (twin vs singleton): 1.40 (0.77-2.55)
Results Comments
Slight increase in breast cancer risk among member of a twin pair, however the result was not significant
Author address
Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115.