ESR1 and breast carcinoma: At first, appropriate patient selection may be a major reason for good results. Our patient had a relatively small unicentric disease (median diameter 1.1 cm) with majorly ER-positive and a negative margin. Next, there may be an ethnic reason. There are inherent and potentially significant differences between Caucasian and Asian patients with breast cancer, reflecting differences in host biology, socioeconomic realities, lifestyle, health-seeking behaviors, and treatment effects. Japanese patients generally showed superior results for systemic agents [15,16].