This prospective cohort study examined the association between combined estrogen and testosterone therapy and the risk of invasive breast cancer in postmenopausal women. Over 24 years, 4,610 cases of invasive breast cancer were identified, with current users of estrogen plus testosterone therapies showing a 2.5-fold increased risk compared to never
This study, conducted within the Nurses’ Health Study cohort, examined the association between hormone replacement therapy (HRT) and breast cancer risk in postmenopausal women over 725,550 person-years, documenting 1,935 cases of invasive breast cancer. Results showed that current users of estrogen alone had a relative risk (RR) of 1.32 (95%
This prospective cohort study investigated the relationship between plasma sex hormone levels and breast cancer risk in 2,886 postmenopausal women using hormone replacement therapy (HRT). The findings showed that higher plasma levels of estrogens and androgens were significantly associated with an increased risk of breast cancer, with women in the
