The efficacy of simple oral nutritional supplements versus usual care in postoperative patients with gastric cancer: study protocol for a multicenter, open-label, parallel, randomized controlled trial

Abstract Background: Oral nutritional supplement (ONS) formulations may lose their flavor because of the complex nutrients used. Many patients who undergo gastrectomy for gastric cancer cannot ingest sufficient amounts of ONS after surgery. Although the use of simpler nutrients in an ONS may improve the flavor, it is unclear if it can prevent the body weight loss (BWL) of patients with gastric cancer after surgery. This study aimed to evaluate the effects of ONS with carbohydrate and protein on BWL, muscle strength, and health-related quality of life (HRQoL). Methods: This will be a multicenter, open-label, parallel, randomized controlled trial in patients with gastric cancer who will undergo gastrectomy. A total of 120 patients who will undergo gastrectomy will be randomly assigned to the ONS group or usual care (control) group in a 1:1 ratio. The stratification factors will be the clinical stage (I or ≥II) and surgical procedures (total gastrectomy or other procedure). In the ONS group, the patients will receive 400 kcal (400 ml)/day of ONS from postoperative day 5 to 7, and the intervention will continue postoperatively for 8 weeks. The control group patients will be given a regular diet. The primary outcome will be the percentage of BWL (%BWL) from baseline to 8 weeks postoperatively. The secondary outcomes will be muscle strength (handgrip strength), HRQoL (EORTC QLQ-C30, QLQ-OG25, EQ-5D-5L), nutritional status (hemoglobin, lymphocyte count, albumin), and dietary intake. All analyses will be performed on an intention-to-treat basis. Discussion: This study will provide evidence showing whether or not ONS with simple nutritional ingredients can improve patient adherence and HRQoL by reducing BWL after gastrectomy. If supported by the study results, nutritional support with simple nutrients will be recommended to patients after gastrectomy for gastric cancer. Trial registration: jRCTs051230012; Japan Registry of Clinical Trails. Registered on Apr. 13, 2023