Sequential adjuvant hormone therapy in postmenopausal breast cancer: rationale and clinical results

For the past 15 years tamoxifen has been the standard adjuvant hormone therapy for women with early-stage breast cancer and estrogen receptor (ER)-positive tumors, irrespective of nodal status and other clinicopathological parameters. Recent studies provided evidence that the optimal duration of tamoxifen treatment is 5 years. Based on the positive clinical results obtained with the administration of aromatase inhibitors (AIs) in the metastatic setting, several controlled clinical trials have evaluated the efficacy and side effects of AIs versus standard tamoxifen also as adjuvant therapy in postmenopausal breast cancer patients. The results of the above studies, suggest a therapeutic advantage of AIs over tamoxifen with regard to relapse-free survival and the risk of metachronous contralateral breast cancer. We review the rationale and the available clinical data on initial or sequential hormone treatment with AIs and we propose a novel scenario for possible therapeutic strategies based on the clinicopathological characteristics of the patients and on the biology of each single tumor.