This study will prospectively collect patients undergoing the standard CROSS regimen in the neoadjuvant setting of the treatment for gastro-oesophageal cancer. The investigators will focus on the potential geometric differences between the OAR and target volume on the initial planning CT and on the kilovolt (kV) cone-beam computed tomography (CBCT). They expect a potential difference in the abdominal part of the planned target volume (PTV) and/or gastro-oesophageal junction part. Furthermore, the impact of gastric filling , potential tumor regression and the accuracy of 5 mm PTV margin in the thoracic PTV will be monitored.