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Hiroyasu Yamashiro received honoraria from Chugai, Daiich-Sankyo, Pfizer, Kyowa Kirin, Eisai, Eli Lilly, Takeda, and Taiho, outside the submitted work. Masahiro Takada received honoraria from Chugai, AstraZeneca, Pfizer, Eli Lilly, Eisai, Daiichi Sankyo, and Kyowa-Kirin as well as grants from Eisai and Nipponkayaku, outside the submitted work. Hiroshi Ishiguro received honoraria from JMS, Taiho, Daiichi-Sankyo, Eisai, Chugai, and Kyowa-Hakko-Kirin outside the submitted work and is on the board of directors of the JBCRG association, Kyoto Breast cancer Research Network; he is also an Executive Committee member of Japan Supportive, Palliative and Psychosocial Oncology Group. Tatsuo Kagimura received grants from Eisai, during the conduct of the study. Tetsuya Taguchi received honoraria from Eisai, Daiichi Sankyo, and Chugai, outside the submitted work. Tomoharu Sugie received honoraria from Chugai, Eisai, Pfizer, Astra Zeneca, Lilly, MSD, Novaris, Takeda, Kyowa-Kirin, Genomic Health, and Devicor as well as grants from KBBM, outside the submitted work. Masakazu Toi received grants and honoraria from Chugai, Takeda, Pfizer, Kyowa-Hakko-Kirin, Taiho, Eisai, Daiichi-Sankyo, Astra Zeneca, Shimadzu, and Nippon Kayaku; honoraria from Eli Lilly, MSD, Genomic Health, Novartis, Konica Minolta, BMS, and Yakult; grants from JBCRG association, Astellas, and AFI technologies, outside the submitted work; and is on the board of directors of the JBCRG association, Organisation for Oncology and Translational Research, and Kyoto Breast cancer Research Network. The remaining authors have no conflicts of interest to disclose.","order":2,"name":"Ethics","group":{"name":"EthicsHeading","label":"Conflict of interest"}},{"value":"The institutional review board at each study site approved the final protocol. 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