Environment and Breast Cancer: Science Review
	Birth characteristics and subsequent risk for breast cancer in very young women
	Innes, K., Byers, T., Schymura, M. Am J Epidemiol. 2000. 152:12, 1121-8.
	 Topic area
Early life exposures
Early life exposures
	 Study design
Population based case-control
Population based case-control
	 Funding agency
NCI
NCI
Study Participants
	 Number of Cases
484
484
	Number  of Controls  
Controls: 2870
Controls: 2870
	 Participant selection: Inclusion and exclusion criteria
	
 Criteria used to select participants in the study.
	In: Cases: All women who were diagnosed with breast cancer in New-York state between 1978 and 1995 and who were also born in New-York state after 1957 and for whom matching with birth record was available.
Controls: the next six liveborn females whose mothers resided in the same county at the time of delivery and who were not subsequently diagnosed with breast or endometrial cancer in New York state.
Ex: controls who died during the first 12 months of life
	 Comment about participation selection
No follow-up of controls after 12 months of life
No follow-up of controls after 12 months of life
	 Exposures investigated
Birthweight, gestational age, preeclampsia, multifetal gestation, maternal age at subject's birth, paternal age
Birthweight, gestational age, preeclampsia, multifetal gestation, maternal age at subject's birth, paternal age
	 How exposure was measured
Other: Birth records
Other: Birth records
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.
	White, African American, other
	 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, parity, 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 conditioned on maternal country of residence, age, and birth date, and additionally adjusted for other intrauterine exposures. Adjusted OR with 95% CI; birthweight >= 4500g versus 2500-3499g; gestational age: <33 versus >=
Conditional logistic regression conditioned on maternal country of residence, age, and birth date, and additionally adjusted for other intrauterine exposures. Adjusted OR with 95% CI; birthweight >= 4500g versus 2500-3499g; gestational age: <33 versus >=
	 Strength of associations reported
Birthweight: 3.10 (1.18-7.97); gestational age: 0.11 (0.16-0.79); preeclampsia: 0.90 (0.36-2.27); multifetal gestation: 1.04 (0.51-2.11); maternal age: 1.94 (1.18-3.18); paternal age: 1.52 (1.03-2.23)
Birthweight: 3.10 (1.18-7.97); gestational age: 0.11 (0.16-0.79); preeclampsia: 0.90 (0.36-2.27); multifetal gestation: 1.04 (0.51-2.11); maternal age: 1.94 (1.18-3.18); paternal age: 1.52 (1.03-2.23)
	 Results Comments
The results suggest a J-shapped relation between a woman's own birth weight and her subsequent risk of developing breast cancer and that high birth weight carries an especially pronounced increase in risk. Severe prematurity appeared to reduce subsequent risk for very early onset breast cancer. There was a finding of a rising breast cancer risk with parental age.
The results suggest a J-shapped relation between a woman's own birth weight and her subsequent risk of developing breast cancer and that high birth weight carries an especially pronounced increase in risk. Severe prematurity appeared to reduce subsequent risk for very early onset breast cancer. There was a finding of a rising breast cancer risk with parental age.
	 Author address
Department of Preventive Medicine and Biometrics, University of Colorado Health Sciences Center, Denver 80262, USA. Kim.Innes@UCHSC.edu
Department of Preventive Medicine and Biometrics, University of Colorado Health Sciences Center, Denver 80262, USA. Kim.Innes@UCHSC.edu
	 Controls participation rate
Not reported
Not reported