Environment and Breast Cancer: Science Review

Evidence From Humans
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Physical activity and breast cancer risk among female physical education and language teachers: a 34-year follow-up
Rintala, P.,, Pukkala, E.,, Laara, E.,, Vikho, V. International Journal of Cancer. 2003. 107, 268-270.
Topic area
Physical Activity
Study design
Prospective cohort
Funding agency
Other: LIKES-Foundation for Promotion of Sport and
Study Participants
Number of Cases
61 physical education teachers 404 language teachers
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Number in Cohort
Cohort: 1489 physical education teachers Cohort: 8560 language teachers
Cohort participation rate
Retention/participation exceeded 70% for exposed a
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: Finnish female physical education or language teachers born after 1920 Ex: emigrated or died; women with prior breast cancers; women with incomplete personal identification codes
Comment about participation selection
Strengths: high participation rate (99%); lengthy follow-up of 34 years (1967-2000); analyzed breast cancer risk amongst physical education teachers by breast cancer risk among language teachers in a population of physical education teachers who were required to participate in physical activities as a major during their university years; stratified results by age Limitations: few physical activity teacher cases, especially after stratifying by age; assumed that language teachers did not participate in physical activities; did not assess the time periods, intensity or the duration of physical activity amongst participants; obtained information through various registries
Exposures investigated
Sedentary lifestyle
How exposure was measured
Job history: Physical education teachers' rosters, National Population Registry and the registry of the Trade Union of Education in Finland
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, confounders: age, calendar period of follow-up, number of children, age at first birth
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
Follow-up: 34 years Effect modifiers: age
Strength of associations reported
No significant association between premenopausal breast cancer and physical activity, Physical education teachers vs. language teachers,
No significant association between postmenopausal breast cancer and physical activity, Physical education teachers vs. language teachers,