In Reply We appreciate the comments from Bazan and White on our phase 3 randomized clinical trial findings.1 We agree that the Korean Radiation Oncology Group (KROG) 08-06 trial did not exclude the need for internal mammary node irradiation (IMNI). We overestimated the benefit of disease-free survival (DFS) while designing our study. As no prospective study results, such as those of the National Cancer Institute of Canada (NCIC) MA.20 trial2 or the European Organisation for Research and Treatment of Cancer (EORTC) 22922 trial,3 were available then, our study was designed based on the results of our previous retrospective study.4 Accordingly, we predicted that the 7-year DFS benefit would be 10% when IMNI was incorporated into regional nodal irradiation compared with when it was not. However, during the study period, the diagnosis and treatment of breast cancer had evolved. Owing to the early detection of breast cancer with the national mass screening program, the tumor stage had been migrated to an earlier stage. Systemic treatment has been developed with the introduction of effective systemic agents, such as taxanes and trastuzumab. These factors resulted in the overall improvement in the treatment outcome in the modern treatment era; thus, between-group improvement in DFS through IMNI further reduced. Therefore, we could not draw a solid conclusion on using IMNI from the KROG 08-06 trial1 owing to the lack of power.