Sex hormone levels, breast cancer risk, and cancer receptor status in postmenopausal women: the ORDET cohort.

Background: Endogenous sex hormone levels have been associated with increased breast cancer risk in postmenopausal women in several prospective studies. However, it remains unclear to what extent serum hormone-breast cancer associations differ with receptor status.

Methods: Associations between serum sex hormone levels and breast cancer risk were assessed in a nested case-control study on postmenopausal women of the ORDET cohort.