CYP19A1 and breast cancer: Nevertheless, it has recently been suggested that women receiving aromatase inhibitors for breast cancer prevention may be at increased risk of cardiovascular diseases, because the oestrogen-lowering effects of such drugs may have adverse effects on blood lipids (Baum et al, 2003; Goss et al, 2003; Atalay et al, 2004; Esteva and Hortobagyi, 2006; Markopoulos et al, 2005).