The evolving role of endocrine therapy for breast cancer

The indirect comparison of LHRH agonist with tamoxifen showed similar efficacy in the adjuvant treatment of premenopausal endocrine-responsive breast cancer patients. Furthermore, LHRH agonist is as effective as cyclophosphamide, methotrexate and 5-fluorouracil chemotherapy. Data concerning combination of LHRH agonist with third-generation aromatase inhibitors are still lacking. Moreover, duration of therapy with LHRH agonist is still a matter of debate. In randomized clinical trials, each of the third-generation aromatase inhibitors (AIs) has demonstrated efficacy in the adjuvant treatment of postmenopausal women with receptor' -positive tumors. Anastrozole has been shown to improve disease-free survival when compared with tamoxifen, letrozole has been shown to further reduce the rate of breast cancer events when given as extended adjuvant therapy in women completing between 4.5 and 6 years of tamoxifen, and exemestane has been shown to improve disease-free survival when substituted for tamoxifen after an initial 2-3 years of adjuvant therapy. Although long-term follow-up for safety and overall survival continues in each of these trials, currently available data suggest that an AI should now be included as part of adjuvant endocrine therapy for the great majority of receptor-positive postmenopausal patients.