Informed

Diet and breast cancer update in the EPIC study

Results from studies on the association between breast cancer and specific dietary factors other than alcohol have so far been inconsistent. However, lifestyle and diet-related factors, such as exposure to oestrogens in the diet and high body fat, are established causes. Research on eating habits, which might influence breast cancer risk either independently or in relation to known risk factors, is ongoing. Here, we report on the findings from two studies in the multi-centre European Prospective Investigation into Cancer and nutrition (EPIC).

Dietary patterns and breast cancer

The first study investigated the association between dietary patterns and breast cancer risk in the French branch of the EPIC study. The study [1] included 65,374 women, of whom 2,381 developed postmenopausal invasive breast cancer after a median 9.7-year follow-up period.

Two dietary patterns were identified: "alcohol/Western" typically associated with meat products, fast foods, eggs, alcoholic beverages, cakes and butter or cream; and "healthy/Mediterranean" characterised by vegetables, fruits, seafood, olive and sunflower oil.

Women eating the Western pattern were 20 per cent more likely to develop postmenopausal breast cancer. The Mediterranean pattern was protective against breast cancer, with a 15 per cent reduction in risk. These associations were more evident among women with oestrogen-related tumours.

These findings are interesting as previous EPIC results [2] did not find a consistent association between intake of meat, eggs, or dairy products and breast cancer.

Coffee and tea consumption

The second study, which used the Netherlands branch of EPIC, analysed the association between coffee and tea consumption and the risk of breast cancer [3]. Of the 27,323 participants, a total of 681 invasive primary breast cancers were diagnosed in 9.6 years of follow-up. The results showed no associations with either coffee or tea intake, dispelling the common myth that coffee might increase breast cancer risk. Although more research is needed, these papers seem to suggest that the overall dietary pattern is probably more important in modulating breast cancer risk than single dietary components.

The best advice currently available for women wanting to reduce breast cancer risk is to maintain a healthy weight, be physically active, eat a low energy-dense diet rich in fruits and vegetables and limit alcohol intake.

References

1. Cottet V et al 2009, Am J Epidemiol, 170(10): 1257-67
2. Pala V et al 2009, Am J Clin Nutr, 90(3): 602-12
3. Bhoo Pathy N et al 2009, Breast Cancer Res Treat DOI 10.1007/s10549-009-0583-y