Environment and Breast Cancer: Science Review

Evidence From Humans
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Preterm birth, birth weight, and subsequent risk of female breast cancer
Kaijser, M., Akre, O., Cnattingius, S., Ekbom, A. Br J Cancer. 2003. 89:9, 1664-6.
Topic area
Early life exposures
Study design
Cohort study
Funding agency
Other: US Army
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Number in Cohort
Cohort: 1483 for birth weight, 1208 for gestational age
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: Female subjects born before 35 completed weeks of gestation according to the date of the last menstruation period, and females born after 35 weeks with a birthweight of less than 2000g, with birth records for the period 1925-1949 from Uppsala University Hospital, Sundsvalls County Hospital, and two major delivery units in Stockholm Ex: Subjects who died before 1958 and subjects with unreasonably high birthweight for gestational age
Comment about participation selection
2 subgroups in the cohort: preterm delivered females (less than 35 weeks) and small for gestational age females (birthweight <2000g and gestational duration >35 weeks)
Exposure Investigated
Exposures investigated
Birthweight, gestational duration
How exposure was measured
Other: Birth records
Exposure assessment comment
Relatively few cases in each category,
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.
Parity, menopausal status, race, alcohol consumption, family history of breast cancer, BMI
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
Standardized incidence ratios for all female breast cancer using age, and time specific cancer incidence rates for the Swedish population during the period 1958-1998. Small for gestational age: birthweight <2000g and gestational duration >35 weeks, birthw
Strength of associations reported
Small for gestational age: 1.09 (0.52-2.01); birthweight: 2.55 (1.03, 5.25); preterm: 1.08 (0.64-1.70)
Results Comments
Neither preterm birth nor low birthweight were associated with an increased risk for breast cancer
Author address
Clinical Epidemiology Unit, Department of Medicine at Karolinska Hospital, M9:01, Karolinska Sjukhuset, S-171 76 Stockholm, Sweden. magnus.kaijser@medks.ki.se