1. Department of Gynecology, Niigata Cancer Center Hospital, Niigata, Japan
2. Department of Obstetrics and Gynecology, Nagaoka Red Cross Hospital, Niigata, Japan
3. Department of Obstetrics and Gynecology, Niigata University Medical and Dental Hospital, Niigata, Japan
4. Department of Pathology, Niigata Cancer Center Hospital, Niigata, Japan