Department of Musculoskeletal Oncology and Rehabilitation Medicine, National Cancer Center Hospital, Rare Cancer Center, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo, 104-0045, Japan. akawai@ncc.go.jp. Rare Cancer Center, National Cancer Center, Tokyo, Japan. akawai@ncc.go.jp. Department of Medical Oncology, Hyogo Prefectural Nishinomiya Hospital, Nishinomiya, Japan. Department of Medical Oncology, The Cancer Institute Hospital of Japanese Foundation for Cancer Research, Tokyo, Japan. Department of Orthopedic Surgery, Mie University Graduate School of Medicine, Tsu, Japan. Department of Orthopedic Surgery, Faculty of Medicine, The University of Tokyo, Tokyo, Japan. Clinical Planning and Development Department, Medical Headquarters, Eisai Co., Ltd., Tokyo, Japan. Department of Musculoskeletal Oncology and Rehabilitation Medicine, National Cancer Center Hospital, Rare Cancer Center, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo, 104-0045, Japan. Rare Cancer Center, National Cancer Center, Tokyo, Japan.