Yasushi Yumura1, Kazumi Noguchi2, Masatoshi Moriyama3, Akira Iwasaki4. 1. Department of Urology, Yokohama City University, Medical Center, Yokohama, Japan. yumura@yokohama-cu.ac.jp. 2. Department of Urology, Yokohama City University, Medical Center, Yokohama, Japan. kazu0825@yokohama-cu. 3. Department of Urology, Yokohama Municipal Citizen's Hospital, Yokohama, Japan. shiminmm@yc4.so-net.ne.jp. 4. Department of Urology, Yokohama Minato Red Cross Hospital, Yokohama, Japan.akiller@sd5.so-net.ne.jp.