Hormonal Treatment of Breast Cancer

Steroid hormones and their receptors play a role in the development and treatment of breast cancer. Endocrine therapy is now a mainstay in the treatment of estrogen receptor-positive breast cancer. In the adjuvant setting, 5 years of endocrine therapy significantly reduce recurrence rate and mortality. Tamoxifen is the molecule of choice for premenopausal women, whereas aromatase inhibitors are currently used for postmenopausal women. Optimal duration and treatment strategies involving adjuvant therapy in early breast cancer are largely discussed, and the benefits of extended adjuvant endocrine therapy beyond 5 years are still controversial. Cases of resistance, de novo or acquired, to endocrine therapy have been described, and emerging therapies are developed to counteract specific mechanisms of resistance.