1Department of Breast Oncology, National Hospital Organization Shikoku Cancer Center, Kou 160, Minamiumemoto-machi, Matsuyama, Ehime, 791-0280 Japan
2Department of Breast Surgery, National Hospital Organization Hokkaido Cancer Center, Sapporo, Japan
3Breast Disease Center, Asahikawa Medical University Hospital, Asahikawa, Japan
4Department of Breast Thyroid Surgery, Kitasato University Hospital, Sagamihara, Japan
5Department of Breast Surgery, Hiroshima City Hiroshima Citizens Hospital, Hiroshima, Japan
6Department of Breast Surgery, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Tokyo, Japan
7Department of Breast Surgery, Matsuyama Red Cross Hospital, Matsuyama, Japan
8Department of Breast Oncology, Gunma Prefectural Cancer Center, Ohta, Japan
9Department of Surgery, National Hospital Organization Nagasaki Medical Center, Nagasaki, Japan
10Department of Breast Surgery, Yao Municipal Hospital, Osaka, Japan
11Department of Breast Oncology, Niigata Cancer Center Hospital, Niigata, Japan
12Department of Breast Surgery, Hyogo Cancer Center Hospital, Kobe, Japan
13Department of Biomedical Statistics and Bioinformatics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
14Department of Surgery, Breast Oncology, National Hospital Organization Osaka National Hospital, Osaka, Japan
15Department of Breast Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
16Breast Oncology Center, The Cancer Institute Hospital of Japanese Foundation for Cancer Research, Tokyo, Japan