1. Division of Gynecologic Oncology, National Hospital Organization Hokkaido Cancer Center, Sapporo, Japan.
2. Division of Obstetrics and Gynecology, Asahikawa Kosei General Hospital, Asahikawa, Japan.
3. Division of Obstetrics and Gynecology, Sapporo Municipal Hospital, Sapporo, Japan.
4. Department of Obstetrics and Gynecology, Hokkaido University School of Medicine, Sapporo, Japan.
5. Division of Pathology, National Hospital Organization Hokkaido Cancer Center, Sapporo, Japan.