EPIC Working Groups - Cancer Working Groups

The Breast Cancer Working Group

Breast cancer is the most common cancer in women worldwide. An important aim of the EPIC Breast Cancer Working Group is to evaluate the impact of lifestyle and diet on breast cancer risk. Since breast cancer is hormone-related, the group also focuses on the role of endogenous and exogenous hormones in breast cancer development.

Breast cancer is now known to be a heterogeneous disease, with different phenotypes, which are likely to have different risk factors. Therefore, the major focus of the Working Group over the past years has been the collection, centralization, and harmonization of receptor status data of tumours, allowing the study of breast cancer risk factors by subtypes.

The main results on breast cancer in EPIC are summarized below.

  • Diet

Overall, results from EPIC found a statistically significant although quantitatively modest increase in risk of breast cancer in relation to consumption of alcohol1 and saturated fat2. The association with saturated fat intake was more evident in postmenopausal women who never used hormone therapy. Overall fruit and vegetable intake was not associated with a significant reduction in breast cancer risk5; however, in postmenopausal women using exogenous hormones, high intakes of beta-carotene and vitamin C were associated with lower risk6.

  • Overweight, obesity, and physical activity

In postmenopausal women, overweight (expressed as body mass index) was a significant predictor of breast cancer risk3. Moderate and high levels of physical activity, combining recreational and household activities, were associated with a reduced risk, independently of the level of overweight4.

  • Endogenous hormones

Data derived from EPIC have also shown that endogenous sex steroid hormones are associated with risk of hormone receptor-positive [estrogen receptor (ER) and progesterone receptor (PR)] breast cancer in postmenopausal women7. This EPIC study focused on women not using hormone replacement therapy, to avoid any interfering effect of hormones taken as medication. Furthermore, in premenopausal women, elevated levels of androgens were associated with an increased risk of breast cancer.

Selected publications:

  1. Tjønneland A et al. Alcohol intake and breast cancer risk: the European Prospective Investigation into Cancer and Nutrition (EPIC). Cancer Causes Control. 2007 May;18(4):361-73. Epub 2007 Feb 15. PMID: 17364225

  2. Sieri S et al. Dietary fat and breast cancer risk in the European Prospective Investigation into Cancer and Nutrition. Am J Clin Nutr. 2008 Nov;88(5):1304-12. PMID: 18996867

  3. Ritte R et al. Adiposity, hormone replacement therapy use and breast cancer risk by age and hormone receptor status: a large prospective cohort study. Breast Cancer Res. 2012 May 14;14(3):R76. PMID: 22583394

  4. Steindorf K et al. Physical activity and risk of breast cancer overall and by hormone receptor status: the European Prospective Investigation into Cancer and Nutrition. Int J Cancer. 2013 Apr 1;132(7):1667-78. PMID: 22903273

  5. van Gils CH et al. Consumption of vegetables and fruits and risk of breast cancer. JAMA. 2005 Jan 12;293(2):183-93. PMID: 15644545

  6. Nagel G et al. Dietary beta-carotene, vitamin C and E intake and breast cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC). Breast Cancer Res Treat. 2010 Feb;119(3):753-65. doi: 10.1007/s10549-009-0444-8. Epub 2009 Jun 30. PMID: 19565333

  7. James RE et al. Postmenopausal serum sex steroids and risk of hormone receptor-positive and -negative breast cancer: a nested case-control study. Cancer Prev Res (Phila). 2011 Oct;4(10):1626-35. PMID: 21813404

Contact details/Working Group leader

Laure Dossus, PhD
Biomarkers Group (BMA)
International Agency for Research on Cancer (IARC/WHO)
150 cours Albert Thomas, 69008 Lyon, France