1. Department of Radiotherapy, Amsterdam UMC, Amsterdam, the Netherlands
2. Verbeeten Institute, Tilburg, the Netherlands
3. Radiotherapeutisch Instituut Friesland, Leeuwarden, the Netherlands
4. Department of Radiation Oncology, School for Oncology and Developmental Biology, Maastricht University, Maastricht, the Netherlands
5. Leids Universitair Medisch Centrum, Leiden, the Netherlands
6. Department of Radiotherapy, Erasmus MC, Rotterdam, the Netherlands
7. Department of Radiotherapy, Catharina Ziekenhuis, Eindhoven, the Netherlands
8. Radiotherapiegroep, Deventer, the Netherlands
9. Department of Radiotherapy, Zeeuws Radiotherapeutisch Instituut, Vlissingen, the Netherlands
10. Department of Surgery, Amsterdam UMC, Amsterdam, the Netherlands
11. Department of Biostatistic, Netherlands Cancer Institute, Amsterdam, the Netherlands
12. Department of Gastroenterology and Hepatology, Amsterdam UMC, Amsterdam, the Netherlands
13. Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam UMC, Amsterdam, the Netherlands
14. Department of Medical Oncology, Erasmus MC, Rotterdam, the Netherlands