1. Department of Medical Oncology, Central University Hospital of Asturias, 33011 Oviedo, Spain
2. Department of Medical Oncology, Hospital Universitario La Paz, 28046 Madrid, Spain
3. Department of Medical Oncology, Hospital de la Santa Creu i Sant Pau, 08025 Barcelona, Spain
4. Instituto de Investigación Sanitaria del Hospital Universitario La Paz (IdiPAZ), 28046 Madrid, Spain
5. Molecular Oncology and Pathology Lab, Institute of Medical and Molecular Genetics-INGEMM, Hospital Universitario La Paz-IdiPAZ, 28046 Madrid, Spain
6. Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid (UAM), 28049 Madrid, Spain
7. Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), 28029 Madrid, Spain
8. Department of Gastroenterology, Hospital Universitario La Paz, 28046 Madrid, Spain
9. Department of Surgery, Hospital Universitario La Paz, 28046 Madrid, Spain
10. Department of Pathology, Hospital Universitario La Paz, 28046 Madrid, Spain
11. Catedra UAM-AMGEN, 28046 Madrid, Spain