Figure 1. Kaplan–Meier curves of disease-free survival and overall survival in the young breast cancer group (n = 196) and the old breast cancer group (n = 227). DFS (disease-free survival) is defined as from the first operation to the first finding of local recurrence (including chest wall, local lymph node, contralateral breast) or distant metastasis. OS (overall survival) is defined as from first operation to the death caused by breast cancer or 5 y until the end of following-up.