In a previous randomized clinical trial against curatively resected gastric cancer, we compared the effect of immunochemotherapy to chemotherapy and obtained significantly better survival and disease-free survival time (DFS) in a combined therapy group. Although DFS was analysed with a conventional approach in which the onset of relapse was defined as the diagnosis of relapse, we considered it necessary to re-analyse the data and compare the results of an interval-censored approach with the conventional approach, in order to examine whether the conclusion might be altered depending on the approach.