IntroductionPatients who underwent curative gastrectomy for gastric cancer are regularly followed-up for the early detection of recurrence and postoperative symptom management. However, there is a lack of evidence with regard to proper surveillance intervals and diagnostic tools. This study aims to evaluate whether frequent surveillance tests have a survival benefit or improve the quality of life in patients who underwent curative resection for advanced gastric cancer.Methods and analysisThe STOFOLUP trial is an investigator-initiated, parallel-assigned, multicentre randomised controlled trial involving 16 hospitals in the Republic of Korea. Patients (n=886) diagnosed with pathological stage II or III gastric adenocarcinoma will be randomised to either the 3-month or the 6-month group at a 1:1 ratio, stratified by trial site and tumour stage. Patients allocated to the 3-month group will undergo an abdominal CT scan every 3 months postoperatively and those allocated to the 6-month group will undergo CT every 6 months. The primary endpoint is 3-year overall survival and the secondary endpoints are quality of life, as assessed using KOrean QUality of life in Stomach cancer patients Study group-40, the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 and the stomach cancer-specific module (STO22), and nutritional outcomes. Other survival data including data concerning 3-year disease-free survival, recurrence-free survival, gastric cancer-specific survival and postrecurrence survival will also be estimated. The first patient was enrolled on July 2021 and active patient enrolment is currently underway.Ethics and disseminationThis study has been approved by the Institutional Review Board of eight of the participating hospitals (NCC 2021-0085, KBSMC2021-01-059, SMC 2021-01-140, KC21OEDE0082, 4-2021-0281, AJIRB-MED-INT-20-608, 2021-0515 and H-2102-093-1198). This study will be disseminated through peer-reviewed publications, national or international conferences.Trial registration numberNCT04740346.