Adjuvant Hormonal Therapy in Women with Early-stage Breast Cancer

For decades, adjuvant hormonal therapy has become the standard treatment of patients with estrogen receptor-positive breast cancer. Currently, the drugs available are GnRH agonists, selective estrogen receptor modulators, and aromatase inhibitors. The use of GnRH agonists represents a potentially reversible treatment that can restore ovarian function after chemotherapy. In premenopausal women, systemic therapy based on selective estrogen receptor modulators administration (e.g., tamoxifen) usually represents the standard adjuvant treatment. There are not sufficient data to recommend the routine addition of GnRH agonists to other endocrine therapies. In postmenopausal women, the disease-free survival was significantly prolonged in patients treated with aromatase inhibitor compared with those treated with tamoxifen, but the survival benefit was modest. Better results were obtained when the two drugs were administered sequentially. According to the ASCO guidelines, after 5 years of tamoxifen treatment, either tamoxifen or aromatase inhibitors therapy should be suggested for an additional 5 years. Unfortunately, most adverse events are consistent with estrogen deprivation and are common to all therapies, and the cumulative toxicity causes discontinuation and nonadherence to therapy in up to 50% of patients. Switching tamoxifen to an aromatase inhibitor may reduce adverse event incidence. Molecular-targeted therapy is useful in patients with advanced, relapsed or hormonal therapy-resistant tumors, usually as second- or third-line treatment. These drugs are usually added to aromatase inhibitors; however, currently, they have not yet been used in patients with early breast cancer.