Department of Breast and Medical Oncology, National Cancer Center Hospital, Tokyo, Japan. Division of Breast and Medical Oncology, National Cancer Center Hospital East, Chiba, Japan. hrmukai@east.ncc.go.jp. Department of Breast Oncology, Saitama Medical University International Medical Center, Saitama, Japan. Graduate School of Cancer Science and Policy, National Cancer Center, Goyang, Korea. Division of Haematology and Oncology, Chang-Gung Memorial Hospital, Linko, Taoyuan, Taiwan. Division of Breast Oncology, Saitama Cancer Center, Saitama, Japan. Center for Breast Cancer, National Cancer Center, Goyang, Korea. Division of Breast Oncology, Shizuoka Cancer Center, Shizuoka, Japan. Department of Breast Surgery, Hiroshima City Hiroshima Citizens Hospital, Hiroshima, Japan. Department of Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea. Department of Surgery, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Tokyo, Japan. Division of Breast and Endocrine Surgery, Department of Surgery, St. Marianna University School of Medicine, Kawasaki, Japan. Department of Breast and Endocrine Surgery, Tokai University School of Medicine, Isehara, Japan. Department of Breast Oncology, Aichi Cancer Center Hospital, Nagoya, Japan. Division of Hematology-Oncology, Samsung Medical Center, Seoul, Korea. Division of Hematology-Oncology, Department of Internal Medicine, Taichung Veterans General Hospital, Taichung, Taiwan. Internal Medicine, College of Medicine, China Medical University, Taichung, Taiwan. Pharmaceuticals Group, Nippon Kayaku Co., Ltd., Tokyo, Japan.