Thursday June 13, 2013 (foodconsumer.org) -- A study published in 1998 in the medical journal the Lancet established an association between circulating concentrations of insulin-like growth factor I and the risk of breast cancer in premenopausal women, but not in postmenopausal women.

Susan E. Hankison from Channing Laboratory in Boston MA and colleagues conducted the study and found premenopausal women in the highest quintile of IGF-I were 133% more likely to be diagnosed with breast cancer, compared with those in the lowest quintile.

Among women younger than 50 years, those in the highest quintile of circulating levels of IGF-I were 358% more likely to be diagnosed with breast cancer, compared with those in the lowest quintile.

The authors of this case-control study, which was part of the prospective Nurses' Health Study, say in their report that IGF-I that promotes proliferation and suppress apoptosis is known to be a risk factor for breast cancer.

Other studies found eating soya foods associated with lower serum levels of IGF-1 while eating animal proteins and red meat was linked to higher IGF-I.  Animal proteins and meat have already been associated with increased risk of cancer in other studies.  Therefore, it is not surprising that IGF-I concentrations are associated with breast cancer risk. (reporting by Jimmy Downs)