Alcohol exposure and breast cancer: results of the women's contraceptive and reproductive experiences study.
OBJECTIVE
To explore associated biological outcomes and clarify the role of timing of exposure in the alcohol-breast cancer relationship.


METHODS
In a population-based study of 4,575 women ages 35 to 64 years diagnosed with invasive breast cancer between 1994 and 1998 and 4,682 controls, we collected details of lifetime alcohol use and factors that could confound or modify the alcohol-breast cancer relationship. We used conditional logistic regression to compute the odds of breast cancer among drinkers relative to nondrinkers at all ages and at ages 35 to 49 and 50 to 64 years separately.


RESULTS
Recent consumption (at reference age minus two) of >/=7 drinks per week was associated with increased risk [odds ratio (OR), 1.2; 95% CI, 1.01-1.3] and evidence of dose response was observed. Most of the excess was observed among women ages 50-64 years (OR 1.3; 95% CI, 1.1-1.6), although the test for age interaction was not statistically significant. Exposure later in life seemed more important than early exposure. Excess breast cancer associated with recent consumption was restricted to localized disease. When outcome was examined according to tumor hormone receptor status, highest risks were observed for estrogen receptor-positive/progesterone receptor-negative tumors (OR 1.6; 95% CI, 1.2-2.3).


CONCLUSIONS
The effect of timing of alcohol exposure on breast cancer risk is complicated and will require additional study focused on this one issue. Further work is needed to explain how alcohol exposure, sex hormones, and tumor receptor status interact.
McDonald
Jill A
JA
National Center for Chronic Disease Prevention and Health Promotion, Division of Reproductive Health, 4770 Buford Highway Northeast, MS-K22, Atlanta, GA 30341-3724, USA.
Mandel
Michele G
MG
Marchbanks
Polly A
PA
Folger
Suzanne G
SG
Daling
Janet R
JR
Ursin
Giske
G
Simon
Michael S
MS
Bernstein
Leslie
L
Strom
Brian L
BL
Norman
Sandra A
SA
Malone
Kathleen E
KE
Weiss
Linda K
LK
Burkman
Ronald T
RT
Weber
Anita L
AL
Spirtas
Robert
R
D000328:Adult; D000367:Age Factors; D000428:Alcohol Drinking / Q000009:adverse effects*; D001943:Breast Neoplasms / Q000209:etiology* / Q000473:pathology; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D011960:Receptors, Estrogen / Q000032:analysis; D011980:Receptors, Progesterone / Q000032:analysis; D012044:Regression Analysis
D011960:Receptors, Estrogen; D011980:Receptors, Progesterone