Environment and Breast Cancer: Science Review

Evidence From Humans
Print this page
Childhood and adult milk consumption and risk of premenopausal breast cancer in a cohort of 48,844 women - the Norwegian women and cancer study
Hjartaker, A., Laake, P., Lund, E. Int J Cancer. 2001. 93:6, 888-93.
Topic area
Diet - Early life exposures
Study design
Prospective cohort
Funding agency
NCI; Norwegian Cancer Society
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Number in Cohort
Cohort 48,844
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: Norwegian women born 1943-57 randomly selected in 1991-1992 to participate in the Norwegian Women and Cancer Study (NOWAC) Ex: Women who said no to participating to the record linkage; women who left blank the 3 questions about milk consumption; 6000 women who received a questionnaire without dietary information; women who died before the start of the follow up; or had a cancer prior to baseline or were lost of follow-up due to change of identification number; and women who emigrated with unknown emigration date. Postmenopausal women at baseline. Women turning 50 years during the follow-up were censored.
Exposure Investigated
How exposure was measured
Questionnaire, self-administered, FFQ
Exposure assessment comment
Few participants in both lower and higher categories of milk intake
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.
Not considered: Race
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
Adjusted RR with 95% CI, highest versus lowest quartile of intake; separate results for milk consumption as a child, as an adult and combined for both periods; mean follow-up 6.2 years
Strength of associations reported
As a child: 0.64 (0.22-1.87); as an adult: 0.56 (0.31-1.01), both: 0.51 (0.27-0.96)
Results Comments
The results suggest an inverse dose-response association between milk consumption and premenopausal breast cancer incidence in a high consumption population.
Author address
Institute of Community Medicine, University of Tromso, Norway. anette.hjartaker@basalmed.uio.no