1. Department of Urology, Abiko Toho Hospital, 1851-1 Abiko, Abiko-shi, Chiba-ken 270-1166, Japan
2. Center for Innovative Research for Communities and Clinical Excellence (CiRC2LE), Fukushima Medical University, 1 Hikarigaoka, Fukushima-shi, Fukushima-ken 960-1295, Japan
3. Department of Urology, Kawasaki Medical School General Medical Center, Okayama, 2-6-1 Nakasange, Kita-ku, Okayama-shi, Okayama-ken 700-8505, Japan