Environment and Breast Cancer: Science Review
About
Carcinogenic and endocrine disrupting effects of cigarette smoke and risk of breast cancer. [see comment]
Band, P. R., Le, N. D., Fang, R., Deschamps, M. Lancet. 2002. 360:9339, 1044-9.
Topic area
Body size
Body size
Study design
Population based case-control
Population based case-control
Funding agency
Other: Worker's Compensation Board of British Colu
Other: Worker's Compensation Board of British Colu
Study Participants
Number of Cases
1,018 (318 pre) (700 post)
1,018 (318 pre) (700 post)
Menopausal Status
Post menopausal
The menopausal status of women included in this study is listed here.
Pre menopausalPost menopausal
Number of Controls
Controls: 1,025 (340 pre) (685 post)
Controls: 1,025 (340 pre) (685 post)
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: women younger than 75 years at baseline who were listed on the population-based British Columbia cancer registry between 6/1/88 and 6/30/89 (cases); Canadian citizen; resident of British Columbia; on the British Columbia provincial voters list (controls)
Ex: cases who had a previous history of breast cancer; controls who had breast cancer diagnosed before 6/30/89
Comment about participation selection
Strengths: obtained histological confirmation diagnosis in all instances; analyzed breast cancer risk in postmenopausal women by BMI and smoking status; selection bias was minimized by the population-based nature of the study; proportion of never smokers and ever smokers was similar among non-responders and responders for cases and controls Limitations: anthropometric data was self-reported; possibility of recall bias and misclassification of age at smoking initiation; small number of cases and controls in subgroups; inability to control for dietary factors; absence of information on second hand smoke inhalation; number of post women who began smoking after a first fullterm pregnancy and had an increase in BMI since early adulthood was small
Strengths: obtained histological confirmation diagnosis in all instances; analyzed breast cancer risk in postmenopausal women by BMI and smoking status; selection bias was minimized by the population-based nature of the study; proportion of never smokers and ever smokers was similar among non-responders and responders for cases and controls Limitations: anthropometric data was self-reported; possibility of recall bias and misclassification of age at smoking initiation; small number of cases and controls in subgroups; inability to control for dietary factors; absence of information on second hand smoke inhalation; number of post women who began smoking after a first fullterm pregnancy and had an increase in BMI since early adulthood was small
Exposure Investigated
Exposures investigated
BMI and change in BMI since age 18
BMI and change in BMI since age 18
How exposure was measured
Questionnaire, self-administered
Questionnaire, self-administered
Exposure assessment comment
Anthropometric data self-reported
Anthropometric data self-reported
Statistical Analysis
Breast cancer outcome investigated
Primary breast cancer
Primary 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.
Adequately controlled, Confounders: age, smoking status, number of cigarettes per day, years of smoking, cigarette pack-years, smoking inhalation in relation to first fullterm pregnancy (before /after)
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
Effect modifiers: smoking status, number of cigarettes per day, years of smoking, cigarette pack-years, smoking inhalation in relation to first fullterm pregnancy (before /after)
Effect modifiers: smoking status, number of cigarettes per day, years of smoking, cigarette pack-years, smoking inhalation in relation to first fullterm pregnancy (before /after)
Strength of associations reported
Breast cancer risk decreased in women who began to smoke after a first fullterm pregnancy and whose BMI was > 21 and increased since age 18, OR=0.49 (0.27-0.89) p=0.02
Breast cancer risk increased in post women that smoked 20 or more cigarettes a day with a BMI > 21 that did not change since age 18, OR=2.37 (1.01-5.58) p=0.05
Breast cancer risk increased in post women with a BMI > 25, OR=2.08 (1.50-2.89) p= <0.001
Breast cancer risk increased in post women whose change in BMI increased since 18 years, OR=1.32 (1.04-1.68) p=0.02
Breast cancer risk decreased in women who began to smoke after a first fullterm pregnancy and whose BMI was > 21 and increased since age 18, OR=0.49 (0.27-0.89) p=0.02
Breast cancer risk increased in post women that smoked 20 or more cigarettes a day with a BMI > 21 that did not change since age 18, OR=2.37 (1.01-5.58) p=0.05
Breast cancer risk increased in post women with a BMI > 25, OR=2.08 (1.50-2.89) p= <0.001
Breast cancer risk increased in post women whose change in BMI increased since 18 years, OR=1.32 (1.04-1.68) p=0.02
Results Comments
Few cases and controls in the subgroups that analyzed breast cancer risk among post women by smoking status and BMI
Few cases and controls in the subgroups that analyzed breast cancer risk among post women by smoking status and BMI
Author address
Health Canada, 1001 Saint-Laurent O, Quebec J4K 1C7, Longueuil, Canada. pierre_band@hc-sc.gc.ca
Health Canada, 1001 Saint-Laurent O, Quebec J4K 1C7, Longueuil, Canada. pierre_band@hc-sc.gc.ca
Controls participation rate
Less than 70% (68.2%)
Less than 70% (68.2%)