Received: 14 April 2017
Accepted: 6 March 2018
First Online: 14 March 2018
Ethics approval and consent to participate
: The concept of the study was approved by the internal ethical committees at all of the 17 institutions involved.The explicit name of the committees was followings;Ethics committee, Akita University Graduate School of Medicine.Ethics committee, University of Tsukuba Faculty of Medicine.Ethics committee, Shiga University of Medical Science.Ethics committee, Kagawa University, Faculty of Medicine.Ethics committee, Tohoku University Graduate School of Medicine.Ethics committee, Hyogo College of Medicine.Ethics committee, Kansai Medical University.Ethics committee, Faculty of Medicine, University of Miyazaki.Ethics committee, Tokai University School of Medicine.Ethics committee, Keio University School of Medicine.Ethics committee, Kyoto University Graduate School of Medicine.Ethics committee, Ibaraki Prefectural Central Hospital.Ethics committee, Kameda Medical Center.Ethics committee, International University of Health and Welfare.Ethics committee, Mito Saiseikai General Hospital.Ethics committee, Tsukuba Medical Center Hospital.Ethics committee, Hitachi General Hospital.
: Informed consent for chemotherapies was obtained from all the patients. Informed consent to participate in the study was not obtained with an opt-out statement on the website of all of the 17 institutions involved because of the retrospective fashion of the study. No patients were 16 years old or below.
: The authors declare that they have no competing interests.
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