Intakes of dietary iron and heme-iron and risk of postmenopausal breast cancer in the National Institutes of Health-AARP Diet and Health Study.
BACKGROUND
Intakes of dietary iron and, in particular, heme iron may increase breast cancer risk because of the prooxidant properties of iron. However, few studies have examined the association of iron and heme-iron intakes with breast cancer risk.


OBJECTIVE
We assessed the association of intakes of dietary iron and heme iron with risk of postmenopausal breast cancer.


METHODS
We used data from the National Institutes of Health-AARP Diet and Health Study to assess intakes of total dietary iron, iron from meat, iron from red meat, and heme iron in relation to breast cancer risk in 116,674 postmenopausal women who completed a detailed questionnaire regarding meat preparation methods and degrees of doneness. During 6.5 y of follow-up, 3396 cases of invasive breast cancer were identified. Cox proportional hazards models were used to compute hazard ratios (HRs) and 95% CIs.


RESULTS
After adjustment for covariates, HRs for the highest compared with the lowest quintiles of intakes of total iron, iron from meat, iron from red meat, and heme iron were all close to unity, and there were no increasing trends with increasing intakes. The multivariable-adjusted HR for the highest compared with the lowest quintile of heme-iron intake was 1.01 (95% CI: 0.89, 1.14; P for trend = 0.97). In addition, no associations were seen when iron variables were stratified by possible effect modifiers or hormone receptor status.


CONCLUSIONS
The results of this large cohort study do not support an association between iron or heme-iron intakes and postmenopausal breast cancer.
Kabat
Geoffrey C
GC
Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY, USA. geoffrey.kabat@einstein.yu.edu
Cross
Amanda J
AJ
Park
Yikyung
Y
Schatzkin
Arthur
A
Hollenbeck
Albert R
AR
Rohan
Thomas E
TE
Sinha
Rashmi
R
D000368:Aged; D001943:Breast Neoplasms / Q000209:etiology*; D015331:Cohort Studies; D005260:Female; D006418:Heme / Q000008:administration & dosage* / Q000494:pharmacology; D006801:Humans; D019266:Iron, Dietary / Q000008:administration & dosage* / Q000494:pharmacology; D008460:Meat; D008875:Middle Aged; D009316:National Institutes of Health (U.S.); D017698:Postmenopause; D016016:Proportional Hazards Models; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014481:United States
D019266:Iron, Dietary; D006418:Heme