Environment and Breast Cancer: Science Review

Dietary carbohydrates and breast cancer risk: a prospective study of the roles of overall glycemic index and glycemic load
Silvera, S. A., Jain, M., Howe, G. R., Miller, A. B., Rohan, T. E. Int J Cancer. 2005. 114:4, 653-8.

Topic area
Diet
Diet
Study design
Prospective cohort
Prospective cohort
Funding agency
NCI Canada
NCI Canada

Study Participants
Number of Cases
1450
1450
Menopausal Status
The menopausal status of women included in this study is listed here.
Postmenopausal and premenopausal separate and combined
Number in Cohort
Cohort 49,111
Cohort 49,111
Cohort participation rate
Not reported
Not reported
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: Women aged 40-59 years at recruitment between 1980 and 1985, participating in the NBSS trial
Ex: Women with extreme energy intake values
Comment about participation selection
Limited exclusion criteria, menopausal status assess only at baseline, not at diagnosis
Limited exclusion criteria, menopausal status assess only at baseline, not at diagnosis

Exposure Investigated
Exposures investigated
Carbohydrates, glycemic index (GI), glycemic load (GL)
Carbohydrates, glycemic index (GI), glycemic load (GL)
How exposure was measured
Questionnaire, self-administered, FFQ
Questionnaire, self-administered, FFQ
Exposure assessment comment
86 food-items questionnaire
86 food-items questionnaire

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.
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.
No
Description of major analysis
Adjusted HR with 95% comparing highest versus lowest quintile, effect modification by menopausal status, subgroup for BMI, interaction of BMI, physical activity and HRT, mean follow-up 16.6 years
Adjusted HR with 95% comparing highest versus lowest quintile, effect modification by menopausal status, subgroup for BMI, interaction of BMI, physical activity and HRT, mean follow-up 16.6 years
Strength of associations reported
Carbohydrate: 0.93 (0.70-1.22), GL: 0.95 (0.79-1.14), GI: 0.88 (0.63-1.22)
Premenopausal: GL: 0.96 (0.76-1.22), GI: 0.78 (0.52-1.16)
Postmenopausal: GL: 1.08 (0.82-1.41), GI: 1.87 (1.18-2.97)
Carbohydrate: 0.93 (0.70-1.22), GL: 0.95 (0.79-1.14), GI: 0.88 (0.63-1.22)
Premenopausal: GL: 0.96 (0.76-1.22), GI: 0.78 (0.52-1.16)
Postmenopausal: GL: 1.08 (0.82-1.41), GI: 1.87 (1.18-2.97)
Results Comments
No association between either overall glycemic index or glycemic load and breast cancer risk over a 16-year follow-up period in the total study population. Postmenopausal women had an increased risk in association with overall glycemic index.
No association between either overall glycemic index or glycemic load and breast cancer risk over a 16-year follow-up period in the total study population. Postmenopausal women had an increased risk in association with overall glycemic index.

Author address
Department of Epidemiology and Population Health, Albert Einstein College of Medicine, New York, NY 10461, USA. ssilvera@aecom.yu.edu
Department of Epidemiology and Population Health, Albert Einstein College of Medicine, New York, NY 10461, USA. ssilvera@aecom.yu.edu