On the other hand, mastectomy is generally considered a sufficient local treatment method for node-negative breast cancer. Nevertheless, a high rate of local recurrence has been reported in a subset of patients with aggressive clinicopathologic factors such as young age, large tumor size, high tumor grade, lymphovascular invasion (LVI), or positive/close resection margin . As the understanding of the molecular biology of breast cancer improves, the biological subtype is receiving attention as a possible prognostic factor with which to distinguish patients with a high versus low risk of local recurrence [5–7]. In the setting of mastectomy, however, the effects of the biological subtype on local recurrence are not consistent [5, 8–10].