Association between alcohol intake and serum sex hormones and peptides differs by tamoxifen use in breast cancer survivors.
OBJECTIVE
To measure the association between alcohol intake and 11 hormones and peptides in postmenopausal breast cancer survivors and to evaluate whether this association differs by tamoxifen use.


METHODS
Self-reported alcohol intake was assessed via food frequency questionnaire on average 30 months post-breast cancer diagnosis in 490 postmenopausal women from three western states. Concurrently, a fasting blood sample was obtained for assay of estrone, estradiol, free estradiol, testosterone, free testosterone, dehydroepiandrosterone sulfate (DHEAS), sex hormone-binding globulin (SHBG), leptin, C-peptide, insulin-like growth factor-I (IGF-I), and IGF-binding protein-3. Adjusted means of these hormones and peptides were calculated for categories of alcohol intake, overall and stratified by tamoxifen use.


RESULTS
The association between alcohol intake and serum hormone and peptide levels differed by tamoxifen use. We found statistically significant inverse associations between alcohol intake and both leptin and SHBG values but only among tamoxifen users. In women not using tamoxifen, we found a positive association between alcohol intake and DHEAS but no association in tamoxifen users.


CONCLUSION
Tamoxifen may modify the association between alcohol intake and serum hormones and peptides. The significant associations found for DHEAS and SHBG are in a direction considered unfavorable for breast cancer prognosis. Postmenopausal breast cancer survivors may benefit from decreasing their alcohol intake.