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Article History

Received: 2 February 2026

Accepted: 18 May 2026

First Online: 29 May 2026

Declarations

Ethics approval and consent to participate: This study was approved by the protocol review committee of the Comprehensive Support Project for Oncological Research of Breast Cancer on March 10, 2018 (approval number T2018-0026) and registered in the UMIN Clinical Trials Registry as UMIN000035863 on February 20, 2019. Ethical approval was obtained from all institutions. The study was conducted in accordance with the legal and regulatory requirements and the general principles of the International Ethical Guidelines for Biomedical Research Involving Human Subjects (Council for International Organizations of Medical Sciences 2002), the Guidelines of Good Clinical Practice (International Conference on Harmonization 1996), and the Declaration of Helsinki (World Medical Association 1996 and 2008). Written informed consent was obtained from all participants.

Consent for publication: Not applicable.

Competing interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: TI has received honoraria from AstraZeneca, Eisai, Daiichi Sankyo, Pfizer, Lilly, Chugai Pharma and MSD. His institution has received research grants from Taiho and Chugai Pharma. YU has received speaker’s bureau fees from Pfizer and honoraria from Chugai Pharma. TS has received speaker’s bureau fees from Pfizer, YK has received honoraria from AstraZeneca, Eisai, Daiichi Sankyo, Pfizer, Taiho, Chugai Pharma, Lilly and Novartis. AY has received honoraria from AstraZeneca, Eisai, Daiichi Sankyo, Pfizer, Lilly, Chugai Pharma, Kyowa Kirin, Takeda, Nipro Corporation and Medica, and Exact Science and research funding from Chugai Pharma and Nippon Kayaku. UT has received speaker’s bureau fees from AstraZeneca, Pfizer, Lilly, Chugai Pharma, Daiichi Sankyo. HY has received honoraria from AstraZeneca, Eisai, Daiichi Sankyo, Pfizer, Lilly, Chugai Pharma and Kyowa Kirin. KN has received honoraria from AstraZeneca, Eisai, Daiichi Sankyo, Pfizer, Lilly, Chugai Pharma, Taiho, and Kyowa Kirin. His institution has received research grants from Daiichi Sankyo, Lilly and Chugai Pharma. HM has received honoraria from Taiho, Daiichi Sankyo and Takeda. All remaining authors have declared no conflicts of interest associated with this study.