Environment and Breast Cancer: Science Review

Evidence From Humans
Print this page
Moderate physical activity in relation to mammographic patterns
Gram, I. T., Funkhouser, E., Tabar, L. Cancer Epidemiology, Biomarkers & Prevention. 1999. 8:2, 117-22.
Topic area
Body size - Physical Activity
Study design
Other: Cross sectional analysis (retrospective cohort)
Funding agency
Other: Norwegian Cancer Society and the Aakre Foun
Study Participants
Number of Cases
542 women whose mammograms were classified as high risk
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Number in Cohort
Cohort: 2720 (1741 pre) (979 post)
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: women age 40-56 years old who participated in the second and third Tromso studies in Norway conducted in 1979-1980 and 1986-1987; women who had mammograms taken during the study; women who had anthropometric measurements taken during the study Ex: diagnosed with breast cancer during the study
Comment about participation selection
Strengths: anthropometric data obtained by trained staff; mammographers were blinded to everything but the age of participants; one of the first studies to examine the relationship between physical activity and mammographic patters or mammographic densities according to BMI; large population based study Limitations: trouble obtaining accurate measures of physical activity; low number of physically active participants; did not obtain information on the temporal relationship between physical activity and mammographic patterns
Exposures investigated
BMI Physical activity
How exposure was measured
Questionnaire, in person Anthropometric measurement, researcher-administered
Breast cancer outcome investigated
Other: high risk mammogram patterns
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, education, menopausal status, number of children, age at first birth, age at menarche, BMI, family history of breast cancer, OC use, alcohol intake and diet
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
Effect modifiers: menopausal status on physical activity and physical activity on BMI
Results Comments
Consistent inverse association between high levels of physical activity and high risk mammographic patterns Women with moderate activity were less likely to have high risk patterns compared with the sedentary women for all of the strata of BMI
Author address
Institute of Community Medicine, University of Tromso, Norway. inger.torhild.gram@ism.uit.no