1. Institute of Molecular Oncology, University Medical Center Göttingen, Germany
2. Department of Medical Stastics, University Medical Center Göttingen, Germany
3. Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Germany
4. Laboratory of Radiobiology & Experimental Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
5. Tumor Biology Department, National Cancer Institute, Cairo University, Cairo, Egypt