Adolescent dietary phytoestrogen intake and breast cancer risk (Canada)

Cancer Causes Control. 2006 Dec;17(10):1253-61. doi: 10.1007/s10552-006-0062-2.


Objective: It has been suggested that dietary phytoestrogen intake during adolescence may reduce the risk of developing breast cancer. This population-based case-control study evaluated the association between adolescent dietary phytoestrogen intake and adult breast cancer risk among women in Ontario, Canada.

Methods: Pathology-confirmed, population-based breast cancer cases, aged 25-74 years, diagnosed between June 2002 and April 2003, were identified using the Ontario Cancer Registry. Population-based controls were recruited, and matched to cases within 5-year age groups. Adolescent phytoestrogen intake was obtained using a brief food frequency questionnaire (n = 3,024 cases, n = 3,420 controls). Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

Results: Higher phytoestrogen intake (both isoflavones and lignans) during adolescence was associated with a reduced breast cancer risk, and a monotonic trend was observed from the lowest to the highest quartile (OR [Q2] = 0.91, 95% CI 0.79-1.04, OR[Q3] = 0.86, 95% CI 0.75-0.98, and OR[Q4] = 0.71, 95% CI 0.62-0.82, p-trend < 0.001).

Conclusion: Adolescent dietary phytoestrogen intake may be associated with a decreased risk of adult breast cancer. If verified, this finding has important implications with regard to breast cancer prevention since diet is a potentially modifiable factor.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Breast Neoplasms* / diet therapy
  • Breast Neoplasms* / prevention & control
  • Canada
  • Case-Control Studies
  • Diet*
  • Disease Susceptibility*
  • Female
  • Humans
  • Odds Ratio
  • Phytoestrogens / administration & dosage*
  • Phytoestrogens / pharmacology*
  • Registries
  • Risk Factors


  • Phytoestrogens