Estrogens and their precursors in postmenopausal women with early breast cancer receiving anastrozole

We demonstrated large inter-individual variability in anastrozole and anastrozole metabolite concentrations as well as E1, E2, E1-C, A, and T concentrations before and while on anastrozole. These findings suggest that the standard 1 mg daily dose of anastrozole is not optimal for a substantial proportion of women with breast cancer.