Environment and Breast Cancer: Science Review

Evidence From Humans
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Body weight correlates with mortality in early-stage breast cancer
Enger, S. M., Greif, J. M., Polikoff, J., Press, M. Archives of Surgery. 2004. 139:9, 954-58; discussion 958-60.
Topic area
Body size
Study design
Retrospective cohort
Funding agency
Other: California Breast Cancer Research Program,
Study Participants
Number of Cases
246 mortalities (invasive only)
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Number in Cohort
Cohort: 1465
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: 24 to 81 years of age at baseline; diagnosed with breast cancer between 1/1/88 and 12/31/95 at the Kaiser Permanente San Diego Medical Center in California; Kaiser health plan members; completed their first course of treatment within the health plan Ex: records with missing vital status or cause of death; missing records
Comment about participation selection
Strengths: analyzed estrogen-receptor status and stage at diagnosis; deaths were confirmed by manually reviewing the patient information from mortality files with information in the health plan files; analyzed breast cancer mortality occurrence by estrogen-receptor status and body weight; anthropometric data was obtained from medical records Limitations: results were not stratified by menopausal status; anthropometric data was obtained at diagnosis, which could have been affected by the disease; did not collect information on weight change after diagnosis; unable to obtain medical records or estrogen-receptor status for all participants in the study; retrospective study
Exposures investigated
Weight and BMI
Statistical Analysis
Breast cancer outcome investigated
Mortality from breast cancer
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, grade, stage, tumor size, lymph node status, and ER status
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: Estrogen-receptor status Follow-up:6.8 years (median) ER+, ER- status noted
Strength of associations reported
Association between breast cancer mortality in women with an early stage breast cancer at diagnosis (I, IIA) and weight, >175 lbs vs. <133, HR=2.39(1.01-5.63) trend p=0.03
Association between breast cancer mortality and weight, >175 lbs vs. <133, HR=1.60(0.99-2.56) trend p=0.14
Results Comments
Women in the upper 50th percentile of weight (>151 lbs) with an early stage of estrogen-receptor negative breast cancer diagnosis had nearly a 5-fold increase in risk of dying compared to women in the lower 50th percentile (<151 lbs) of weight with an early stage of estrogen-receptor negative breast cancer diagnosis.
Author address
Department of Research and Evaluation, Kaiser Permanente of Southern California, Pasadena, CA, USA.