To evaluate the long-term outcomes beyond 10 years of the Korean Breast Cancer Society-sponsored multicenter prospective ASTRRA trial, we aim to compare the effects of adding 2 years of ovarian function suppression (OFS) therapy to standard tamoxifen treatment in premenopausal young women with hormone receptor-positive breast cancer who preserved or recovered ovarian function after chemotherapy. Given the characteristic pattern of delayed recurrence in hormone receptor-positive breast cancer compared with other molecular subtypes, this long-term follow-up study will assess the durability and safety of the treatment strategy by evaluating disease-free survival (DFS) beyond 10 years, breast cancer-specific survival, and overall survival. In addition, through analyses of recurrence patterns according to treatment groups, we aim to determine the long-term impact of additional OFS therapy on reducing different types of recurrence.
