American Journal of Epidemiology Advance Access published online on March 15, 2008
American Journal of Epidemiology, doi:10.1093/aje/kwn027
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ORIGINAL CONTRIBUTION |
A Prospective Study of Multivitamin Supplement Use and Risk of Breast Cancer
1 Division of Preventive Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA
2 Department of Obstetrics and Gynecology, Tokyo Women's Medical University, Tokyo, Japan
3 Department of Epidemiology, Harvard School of Public Health, Boston, MA
4 Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA
5 Department of Ambulatory Care and Prevention, Harvard Medical School, Boston, MA
Correspondence to Dr. Shumin M. Zhang, Division of Preventive Medicine, Brigham and Women's Hospital, 900 Commonwealth Avenue East, Boston, MA 02215 (e-mail: shumin.zhang{at}channing.harvard.edu).
Received for publication September 20, 2007. Accepted for publication January 28, 2008.
The authors evaluated the association between multivitamin supplement use and breast cancer risk in a completed trial. At baseline (1992–1995), 37,920 US women aged 
45 years and free of cancer provided detailed information on multivitamin supplement use. During an average of 10 years of follow-up, 1,171 cases of invasive breast cancer were documented. Multivitamin use was not significantly associated with overall risk of breast cancer. Compared with the risk for never users, the multivariable relative risks were 0.97 (95% confidence interval: 0.81, 1.16) for past users and 0.99 (95% confidence interval: 0.82, 1.19) for current users. Current multivitamin use for 20 years or 6 times/week was also not significantly associated with risk. Multivitamin use was nonsignificantly inversely associated with risk of breast cancer among women consuming 10 g/day of alcohol and with risk of estrogen receptor negative–progesterone receptor negative breast cancer. Multivitamin use was nonsignificantly associated with a reduced risk of developing 
2-cm breast tumors but an increased risk of >2-cm tumors. The authors' data indicate no overall association between multivitamin use and breast cancer risk but suggest that multivitamin use might reduce risk for women consuming alcohol or decrease risk of estrogen receptor negative–progesterone receptor negative breast cancer.
alcohol drinking; breast neoplasms; receptors, estrogen; receptors, progesterone; vitamins
Abbreviations: CI, confidence interval; ER, estrogen receptor; PR, progesterone receptor; RR, relative risk