A study led by researchers at Queen Mary University of London found that new breast cancer prevention treatments were most effective in women with elevated estrogen levels. Findings published in the journal Lancet Oncology confirm that high levels of this hormone are a risk factor for breast cancer in postmenopausal women.

Newly approved aromatase inhibitors such as anastrozole have recently gained approval for the prevention of breast cancer and have been shown to be particularly effective in postmenopausal women at high risk for the disease. An analysis of data from the IBIS-II study, which included 212 women, found that women with elevated estrogen levels benefited most from anastrozole, with a 55% reduction in cancer risk.

While in women with low levels of the hormone, the risk decreased by only 25%.

Authors of the study, including Prof. Jack Cusick, noted that a simple analysis of blood hormone levels could help improve the effectiveness of anastrozole by selecting the most appropriate patients. Thus, this study confirms the importance of an individualized approach in breast cancer prevention.