This study aims to develop a Social Cognitive Theory (SCT)-based dietary behavioral intervention for gastric cancer survivors, and explore the feasibility, acceptability, and preliminary effectiveness of delivering this intervention. This study includes two phases: intervention development in phase 1 and a pilot randomized controlled trial (RCT) in phase 2.

During phase 1, the initial intervention protocol has been developed based on the SCT and literature review, which was further refined and/or enriched based on evidences from a qualitative descriptive study and an expert consultation. The qualitative descriptive study has been conducted from July to November 2021, and the expert consultation has been conducted from December 2021 to January 2022. For the qualitative descriptive study, purposive sampling was used to select eligible participants in patients who had a gastrectomy within two years from a tertiary hospital in Wuhan city, China. Three focus group interviews were performed with 13 participants via WeChat. Interviews were audio-recorded, transcribed verbatim, and analyzed using conventional qualitative content analysis. Data collection and analysis proceeded simultaneously until data saturation was reached. For the expert consultation, six experts majoring in nursing, digestive oncology, or nutrition were invited to assess the content validity of the intervention protocol. Data analysis of the qualitative descriptive study and the expert consultation is ongoing.

During phase 2, the pilot RCT for testing the feasibility, acceptability, and preliminary effectiveness of the proposed intervention is started. All participants are recruited through convenience sampling from a tertiary hospital in Wuhan city, China. Sample size of the pilot RCT is proposed to be 72. After randomization, the participants are assigned to one of two groups, either the intervention group, which receive a 4-week dietary behavioral intervention; or the control group, which receive usual care only. The 4-week dietary behavioral intervention targets six dietary behaviors related to gastric cancer and is delivered by a registered nurse who has received around 32 hours of nutrition training. The intervention includes one session of face-to-face education and three sessions of telephone counselling; all sessions are individual based. The usual care is general dietary advice provided by the ward nurses before discharge. The general dietary advice is provided orally and printed in the discharge plan. The primary outcomes are feasibility and acceptability. The secondary outcomes include dietary consumption, quality of life, and self-efficacy. Outcome measurements are conducted at baseline (before randomization), and week 5 (after intervention). Generalized estimating equation model analyses will be conducted to examine group-by-time interaction effects.

Inclusion Criteria:

• Adult aged 18 years or above；
• A confirmed diagnosis of gastric cancer (stage I-III)；
• Completed primary cancer treatments including surgery, and/or chemotherapy， and/or radiotherapy；
• Currently free of cancer；
• Able to read, write and speak Mandarin.

Exclusion Criteria:

• Unable to eat orally；
• With poor performance status as determined by the Eastern Cooperative Oncology Group (ECOG) scores ≥ 2;
• With poor cognitive status as determined by the Montreal Cognitive Assessment 5 minute Test <11;
• Taking part in other dietary interventions or under regular follow-up by a dietitian.