Aromasin® (Exemestane) was approved in China for adjuvant treatment of postmenopausal women with estrogen receptor (ER) positive early invasive breast cancer who have received 2-3 years of tamoxifen & are switched to Aromasin® for completion of a total of 5 consecutive years of adjuvant hormonal therapy by State Food and Drug Administration (SFDA) with clinical trial waive. While Aromasin® has been used in China for adjuvant therapy of breast cancer since then, there is currently lack of systematic collection and analysis for the efficacy and safety data of Aromasin® adjuvant setting in Chinese population. The Aromasin® Non-Interventional Study is being proposed to collect data systematically and to assess the efficacy and safety of Aromasin® adjuvant setting in Chinese population.