Prognostic impact of postoperative radiotherapy in patients with breast cancer and with pT1-2 and 1-3 lymph node metastases: A retrospective cohort study based on the Japanese Breast Cancer Registry

Akimitsu Yamada 1, Naoki Hayashi 2, Hiraku Kumamaru 3, Masayuki Nagahashi 4, Shiori Usune 5, Sota Asaga 6, Kotaro Iijima 7, Takayuki Kadoya 8, Yasuyuki Kojima 9, Makoto Kubo 10, Minoru Miyashita 11, Hiroaki Miyata 12, Etsuko Ogo 13, Kenji Tamura 14, Kenta Tanakura 15, Keiichiro Tada 16, Naoki Niikura 17, Masayuki Yoshida 18, Shinji Ohno 19, Takashi Ishikawa 20, Kazutaka Narui 21, Itaru Endo 22, Shigeru Imoto 23, Hiromitsu Jinno 24 1Department of Breast Surgery, Yokohama City University Hospital, 3-9 Fukuura, Kanazawa-ward, Yokohama, Kanagawa, 236-0004 Japan. Electronic address: ayamada@yokohama-cu.ac.jp. 2Department of Breast Surgical Oncology, St. Luke's International Hospital, 9-1 Akashicho, Chuou-ward, Tokyo, 104-8560, Japan. Electronic address: naokiha@luke.ac.jp. 3Department of Healthcare Quality Assessment, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ward, Tokyo, 113-8655, Japan. Electronic address: hik205@mail.harvard.edu. 4Department of Surgery, Division of Breast and Endocrine Surgery, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya City, Hyogo, 663-8501, Japan. Electronic address: ma-nagahashi@hyo-med.ac.jp. 5Department of Healthcare Quality Assessment, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ward, Tokyo, 113-8655, Japan. Electronic address: susune6256@gmail.com. 6Department of Breast Surgery, Kyorin University Hospital, 6-20-2, Arakawa, Mitaka, Tokyo, 181-8611, Japan. Electronic address: asaga@agate.dti.ne.jp. 7Department of Breast Oncology, Juntendo University, 3-1-3 Hongo, Bunkyo-ku, Tokyo, 113-8431, Japan. Electronic address: k-iijima@juntendo.ac.jp. 8Department of Surgical Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-0037, Japan. Electronic address: takayukikadoya@gmail.com. 9Division of Breast and Endocrine Surgery, Department of Surgery, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-ku, Kawasaki, Kanagawa, 216-8111, Japan. Electronic address: kojiyasu@marianna-u.ac.jp. 10Department of Surgery and Oncology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. Electronic address: mkubox0712@gmail.com. 11Department of Breast and Endocrine Surgical Oncology, Tohoku University School of Medicine, Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan. Electronic address: atihsayim8m8@med.tohoku.ac.jp. 12Department of Healthcare Quality Assessment, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ward, Tokyo, 113-8655, Japan. Electronic address: h-m@keio.jp. 13Department of Radiology, Kurume University School of Medicine, 67 Asahi-Machi, Kurume, Fukuoka, 830-0011, Japan. Electronic address: etsuogo@med.kurume-u.ac.jp. 14Cancer Genome Center, Shimane University Faculty of Medicine, 89-1 Shioharucho, Izumo, Shimane, 693-8501, Japan. Electronic address: ketamura@med.shimane-u.ac.jp. 15Department of Plastic and Reconstructive Surgery, Mitsui Memorial Hospital, 1 Kanda Izumicho, Chiyoda-ku, Tokyo, 101-8643, Japan. Electronic address: kenta.tanakura@jfcr.or.jp. 16Department of Breast and Endocrine Surgery, Nihon University School of Medicine, 30-1 Oyaguchikami-cho, Itabashi-ku, Tokyo, 173-8610, Japan. Electronic address: ktada-tky@umin.ac.jp. 17Department of Breast and Endocrine Surgery, Tokai University School of Medicine, 143, Shimokasuya, Isehara, Kanagawa, Japan. Electronic address: niikura@is.icc.u-tokai.ac.jp. 18Department of Diagnostic Pathology, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo, 104-0045, Japan. Electronic address: masayosh@ncc.go.jp. 19Breast Oncology Center, Cancer Institute Hospital, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan. Electronic address: shinji.ohno@jfcr.or.jp. 20Department of Breast Disease, Tokyo Medical University Hospital, 6-1-1 Sinjuku, Shinjuku-ward, Tokyo, 160-8402, Japan. Electronic address: tishik55@gmail.com. 21Department of Breast and Thyroid Surgery, Yokohama City University Medical Center, 4-57 Urafunecho, Minami-ward, Yokohama, Kanagawa, 232-0024, Japan. Electronic address: nr158@yokohama-cu.ac.jp. 22Department of Breast Surgery, Yokohama City University Hospital, 3-9 Fukuura, Kanazawa-ward, Yokohama, Kanagawa, 236-0004 Japan. Electronic address: endoit@yokohama-cu.ac.jp. 23Department of Breast Surgery, Kyorin University Hospital, 6-20-2, Arakawa, Mitaka, Tokyo, 181-8611, Japan. Electronic address: imoto@ks.kyorin-u.ac.jp. 24Department of Surgery, Teikyo University School of Medicine, 2-11-1, Kaga, Itabashi-ward, Tokyo, 173-8606, Japan. Electronic address: jinno@med.teikyo-u.ac.jp.

Tamura, Kenji