1. Department of Oncology Surgery, Tangshan People's Hospital, Tangshan, Hebei 063000, P.R. China
2. Department of Gynaecology, Tangshan Hongci Hospital, Tangshan, Hebei 063000, P.R. China
3. Health Department of Kailuan (Group), Kailuan General Hospital, Tangshan, Hebei 063000, P.R. China