RESUMEN
The goal of adjuvant endocrine therapy for early breast cancer is to prolong overall survival and improve the quality of life of patients. Studies on breast cancer show an early peak of recurrence at two years after surgery and distant recurrences that are responsible for a significant reduction in overall survival. Tamoxifen has been the standard of adjuvant endocrine therapy in breast cancer for years, however only about half of relapses are prevented and there is an early occurrence of serious adverse events due to agonistic estrogenic activity of tamoxifen, such as an increase in the risk of endometrial hyperplasia and venous thromboembolism. The use of aromatase inhibitors is changing this standard with studies covering various clinical settings. They have shown a benefit in many situations, such as an extension of endocrine therapy by tamoxifen, sequential hormonotherapy or up-front adjuvant therapy with aromatase inhibitors