Alcohol and folate intake and breast cancer risk in the WHI Observational Study.
BACKGROUND
Alcohol increases breast cancer risk. Epidemiological studies suggest folate may modify this relationship.


OBJECTIVE
To examine the relationship among breast cancer, alcohol and folate in the Women's Health Initiative-Observational Study (WHI-OS).


METHODS
88,530 postmenopausal women 50-79 years completed baseline questionnaires between October 1993 and December 1998, which addressed alcohol and folate intake and breast cancer risk factors. Cox proportional hazards analysis examined the relationship between self-reported baseline alcohol and folate intake and incident breast cancer.


RESULTS
1,783 breast cancer cases occurred over 5 years. Alcohol was associated with increased risk of breast cancer (RR = 1.005, 95%CI 1.001-1.009). Risk increased with consumption of alcohol (up to 5 g/d, adjusted HR = 1.10, 95%CI 0.96-1.32; >5-15 g/d HR = 1.14, 95%CI 0.99-1.31; and >15 g/d HR = 1.13 95%CI 0.96-1.32). We found no significant interaction between alcohol and folate in our adjusted model.


CONCLUSIONS
We found no evidence for folate attenuating alcohol's effect on breast cancer risk in postmenopausal women. Our results may be due to misclassification of folate intake or the relatively short follow-up period.
Duffy
Christine M
CM
Division of General Internal Medicine, Rhode Island Hospital, Brown University Medical School, Providence, RI 02903, USA. cduffy@lifepsan.org
Assaf
Annlouise
A
Cyr
Michele
M
Burkholder
Gary
G
Coccio
Elizabeth
E
Rohan
Tom
T
McTiernan
Anne
A
Paskett
Electra
E
Lane
Dorothy
D
Chetty
V K
VK
D000368:Aged; D000428:Alcohol Drinking / Q000009:adverse effects*; D001943:Breast Neoplasms / Q000209:etiology* / Q000378:metabolism; D015331:Cohort Studies; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage* / Q000494:pharmacology; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D017698:Postmenopause; D011446:Prospective Studies; D016387:Women's Health
D005492:Folic Acid
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