Environment and Breast Cancer: Science Review

Evidence From Humans
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Steroid metabolism gene CYP17 polymorphism and development of breast cancer
Mitrunen, K. , Jourenkova, N., Kataja, V., Eskelinen, M., Kosma, V. M., Benhamou, S., Vainio, H., Uusirupa, M., Hirvonen, A. Cancer Epidemiology, Biomarkers and Prevention. 2000. 9, 1343-1348.
Topic area
Body size - Genetic variability
Study design
Population based case-control study
Funding agency
Other: Academy of Finland, Finnish Konkordia Found
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Cases were women referred to university hospital for suspicious breast symptoms, recruited prior to diagnosis; participants of the Kuopio Breast Cancer Study. Healthy controls drawn from Finnish National Population Register covering same catchment area as cases.
Exposures investigated
BMI, CYP17 allele frequencies, used PCR-RFLP
How exposure was measured
Biological Questionnaire, in-person
Statistical Analysis
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.
Adequately controlled
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
Logistic regression analysis of CYP17 genotype and breast cancer, including effect modification by BMI
Strength of associations reported
No association between A2 allele and overall breast cancer risk in crude associations
In analyses stratified by menopausal status and tumor stage, premenopausal women with advanced disease who carried the A2 allele showed a nonsignificant lower risk with an adjusted OR=0.58 (CI: 0.31-1.07); No association in postmenopausal women;No significant association between A2 allele genotypes and local v. advanced disease
In analysis stratified by menopausal status and BMI, only postmenopausal women with BMI >25.4 showed an increased risk OR=1.70 approaching significance (0.98-2.94)
Results Comments
Authors note that their study, though large, barely reached 90% power at p=.05 to detect a 1.5 fold effect in risk