Key Points
ÎAdjuvant endocrine therapy for hormone receptor-positive (HR+) breast cancer consists of 3 strategies:
> Primary – for patients who have not had prior endocrine (tamoxifen or AI) therapy > Sequential – for patients who have completed two to three years of tamoxifen or an AI
> Extended – for patients who have completed five years of adjuvant tamoxifen
ÎEndocrine therapy is effective only among patients with tumors that express estrogen receptor (ER) and/or progesterone receptor (PR) hormone receptors.
ÎAdjuvant endocrine therapy reduces the risk of breast cancer recurrence, prolongs disease-free survival, and improves overall survival among women with HR+ breast cancer.
ÎAdjuvant endocrine therapy reduces breast cancer events including locoregional recurrence, contralateral breast cancer, and early distant metastatic recurrence.
ÎAt present, tamoxifen and aromatase inhibitor (AI)-based therapy are equivalent in terms of overall survival when used as either a primary or extended treatment strategy.
ÎMost postmenopausal women with hormone receptor-positive breast cancer should be offered an aromatase inhibitor during the course of adjuvant treatment.
> Primary adjuvant therapy or therapy following two to three years of tamoxifen yields equivalent outcomes in prospective studies.
ÎTherapy with an aromatase inhibitor should not extend beyond five years in either the primary or extended adjuvant settings, outside of the clinical trials setting.
> In the sequential setting, patients should receive an AI after two or three years of tamoxifen for a total of five years of adjuvant endocrine therapy.
ÎPatients who initially receive tamoxifen as adjuvant therapy may be offered an AI after two to three years (sequential) or after five years (extended) of therapy.
> The time to switch from an AI to tamoxifen (or the converse) that maximally improves outcomes is not known from available direct evidence.
> Patients who are initially treated with an AI but discontinue treatment before five years of therapy should consider taking tamoxifen for a total of five years of adjuvant endocrine therapy.
