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Article History

Received: 2 June 2020

Accepted: 5 November 2020

First Online: 6 January 2021

Compliance with ethical standards

:

: Dr. Saito reports personal fees from AstraZeneca, during the conduct of the study, personal fees from Chugai Pharmaceutical, and personal fees from Ono Pharmaceutical, outside the submitted work; Dr. Iwasawa reports personal fees from Daiichi Sankyo Company, Limited, personal fees from AstraZeneca K.K., personal fees from Bristol-Myers Squibb K.K., personal fees from MSD K.K., grants and personal fees from Ono Pharmaceutical Co., Ltd., during the conduct of the study, and personal fees from Chugai Pharmaceutical Co., Ltd., outside the submitted work; Dr. Takiguchi reports grants and personal fees from Novartis, grants from Daiichi Sankyo, personal fees from AstraZeneca, during the conduct of the study, grants and personal fees from Eli Lilly, grants and personal fees from Chugai Pharmaceutical Co., grants and personal fees from MSD, grants from Takeda, grants and personal fees from Taiho Pharmaceutical Co., grants from Kyowa-Hakko Kirin, grants and personal fees from Boehringer Ingelheim, grants and personal fees from Ono Pharmaceutical Co., and grants and personal fees from Bristol Meyers Squib, outside the submitted work; Dr. Ebata, Dr. Ishiwata, Dr. Yoshino, and Dr. Tatsumi have nothing to disclose.

: The institutional review board of the Chiba University Hospital approved the study protocol (approval no.2634).

: Given the retrospective nature and the anonymous design of our study, written informed consent was not obtained from patients, who were however provided with the opportunity to opt out of their confidential patient information being used for research using our institutional website.

: We provided all patients with the opportunity to opt out of their confidential patient information being used for research using our institutional website.

: Not applicable.