1. School of Public Health Department of Biostatistics and Epidemiology, Addis Ababa University, Ethiopia
2. Institute of Medical Epidemiology, Biometrics and Informatics, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
3. America Cancer Society, Atlanta, Georgia, USA
4. City of Hope National Medical Center, Duarte, California, USA
5. Department of Gynaecology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany