Serum concentrations of total and non‐protein‐bound oestradiol in patients with breast cancer and in normal controls

Abstract

In premenopausal women with breast cancer, total serum estradiol (E2) concentrations are normal but non-protein-bound E2 concentrations are significantly raised. This is not due to low sex-hormone-binding-globulin (SHBG) binding capacities which are within the normal range, and is unlikely to be due to the small but significant decrease in albumin concentrations. In postmenopausal patients, total and non-protein-bound E2 are significantly raised: this may be explained partially by lower SHBG binding capacities. In patients and controls there is a highly significant correlation between non-protein-bound E2 and SHBG but, for a given SHBG binding capacity, the patients have more non-bound E2 than controls. The breast in women with breast cancer may be exposed to elevated levels of biologically active E2, although the reasons for this remain obscure. [These results are discussed in relation to the etiology of breast cancer.].