Background: Despite recent improvements in oncological and surgical treatment for patients with oesophageal and gastric cancer, 60% of patients with locally advanced disease who are treated with a curative intent will develop tumour recurrence and die within three years of completing treatment. In the absence of robust scientific evidence national or international guidelines have failed to reach consensus on the optimal surveillance strategy after primary treatment of oesophageal or gastric cancer. Methods: The primary research question of the proposed randomised controlled trial (RCT) is does the routine use of a structured follow-up program with regular radiological and endoscopic investigations improve survival in patients who have had surgical treatment for oesophageal or gastric cancer with curative intent? We aim to assess whether structured follow-up, including radiological and endoscopic investigations after completing curatively intended treatment, improves survival in patients with oesophageal or gastric cancer. The secondary aims of this RCT are to determine the impact of a structured post-treatment surveillance upon the detection and treatment of cancer recurrence and health-related quality of life, including anxiety and to assess the cost-effectiveness. We will undertake a national prospective, multi-centre, randomised controlled trial of structured follow-up including radiological and endoscopic investigations versus standard clinical follow-up. The setting will be at least 24 large oesophago-gastric cancer UK cancer centres. We will aim to recruit 952 oesophageal and gastric cancer patients receiving surgical resection for curatively intended treatment of oesophageal or gastric cancer +/- neoadjuvant/adjuvant chemo(radio or immuno)therapy. At 4-12 weeks after surgery for oesophageal or gastric cancer, patients will be assessed for eligibility for inclusion in the trial. Patients will be randomised 1:1 to receive either intensive follow-up for up to 3-years, with clinical and computerised tomography (CT) investigation every 6 months, and an endoscopy at 12 months or to current standard NHS follow-up, i.e. clinical review at 6 and 12 months followed by targeted investigation as required based upon the onset of new symptoms. The primary outcome is 3-year all-cause mortality and secondary outcomes include health-related quality of life (including anxiety), 3-year disease-specific mortality, pattern and treatment of tumour recurrence, and cost-effectiveness of follow-up in both study arms. The findings of this RCT will inform national and international guidelines for patients with oesophageal and gastric cancer, as this will be the first RCT to provide robust evidence concerning the value of surveillance in this population. Clinical trial information: 14417629.