Original Paper

Cancer Causes & Control

, Volume 20, Issue 7, pp 1083-1090

First online:

Exposure to breast milk in infancy and risk of breast cancer

  • Lauren A. WiseAffiliated withSlone Epidemiology Center, Boston University Email author 
  • , Linda Titus-ErnstoffAffiliated withDartmouth Medical School, Norris Cotton Cancer Center and Hood Center for Children and Families
  • , Polly A. NewcombAffiliated withPaul P. Carbone Comprehensive Cancer Center, University of WisconsinCancer Prevention Program, Fred Hutchinson Cancer Research Center
  • , Amy Trentham-DietzAffiliated withPaul P. Carbone Comprehensive Cancer Center, University of WisconsinDepartment of Population Health Sciences, University of Wisconsin-Madison
  • , Dimitrios TrichopoulosAffiliated withDepartment of Epidemiology, Harvard School of Public Health
  • , John M. HamptonAffiliated withPaul P. Carbone Comprehensive Cancer Center, University of Wisconsin
  • , Kathleen M. EganAffiliated withH. Lee Moffitt Cancer Center and Research Institute, Medical Research Center

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Early life exposures, such as being breastfed in infancy, may influence the risk of breast cancer in adulthood. We evaluated the risk of breast cancer in relation to ever having been breastfed in infancy among 9,442 women who participated in a population-based, case–control study. Cases were identified through cancer registries in three states (Massachusetts, New Hampshire, and Wisconsin); controls were identified through statewide drivers’ license lists or medicare lists. Data on known and suspected risk factors were obtained through telephone interview. We used unconditional logistic regression to assess the relation of breast cancer with ever having been breastfed and with breastfeeding duration (available for only 19% of breastfed women) in premenopausal women (1,986 cases and 1,760 controls) and postmenopausal women (2,600 cases and 2,493 controls). We found no evidence that ever having been breastfed in infancy was associated with breast cancer risk in either premenopausal women (odds ratio [OR] = 0.96; 95% confidence interval [CI] = 0.83–1.10) or postmenopausal women (OR = 0.98; 95% CI = 0.87–1.10). The association did not differ according to breast cancer stage, mother’s history of breast cancer, or any other reproductive factor assessed. Likewise, we found no association between breastfeeding duration and risk of breast cancer. Our results did not support the hypothesis that exposure to breast milk in infancy influences the risk of adult breast cancer.


Breast cancer Breastfeeding Menopausal status Risk factors