1. Department of Biochemistry, Tulane University Health Sciences Center, New Orleans, Louisiana, USA
2. Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, Michigan, USA
3. Department of Epidemiology, University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA
4. Gastrointestinal Surgery Center, Mansoura University, Mansoura, Egypt
5. Division of Pathology and Laboratory Medicine, and
6. Department of Gastrointestinal Medical Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA
7. Department of Mathematics, Tulane University, New Orleans, Louisiana, USA