1. Department of Surgical Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
2. Department of Surgery, Hepato-Bilio-Pancreatic Surgery Unit, Clinica Alemana, Santiago, Chile
3. Department of Biostatistics, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
4. Department of Digestive Surgery, Hepato-Bilio-Pancreatic Surgery Unit, Surgery Service, Hospital Sotero Del Rio, Santiago, Chile
5. Department of Digestive Surgery, Faculty of Medicine, Pontificia Universidad Catolica de Chile, Santiago, Chile
6. Department of Biostatistics, Clínica Alemana-Universidad del Desarrollo, Santiago, Chile