Developing and Testing the Effectiveness of Smart Healthcare Assisted Individualized Symptom Management Education and Home-based Exercise on Frailty, Treatment-related Adverse Events and Quality of Life in Advanced Gastric Cancer Patients Receiving Immunotherapy

The goal of this randomized controlled intervention is to develop and evaluate the effectiveness of the nurse-led with AI chatbot Individualized Symptom Management Education and Home-based Exercise (AI-ISME\&HE) based on The Theory of Symptom Self-Management (TSSM) on frailty, self-efficacy in cancer care, trAE, and quality of life in advanced gastric cancer patients receiving immunotherapy. The main questions it aims to answer are: * Can AI-ISME\&HE reduces frailty in advanced gastric cancer patients receiving immunotherapy? * Can AI-ISME\&HE increases quality of life in advanced gastric cancer patients receiving immunotherapy? * Can AI-ISME\&HE increases self-efficacy in advanced gastric cancer patients receiving immunotherapy? * Can AI-ISME\&HE reduces all-caused death in advanced gastric cancer patients receiving immunotherapy within two years? Researchers will compare usual routine care to see if AI-ISME\&HE can reduce frailty, all-caused death and increase quality of life and self-efficacy. Participants will not be blinded, but the outcome evaluator will be blinded. The participants will be asked to complete three tasks for 12 weeks: * Self-reporting treatment-related adverse events * Interacting with AI-ISME\&HE for seeking information related to self-management educational materials, including symptom management with the most reported trAEs and prevention from frailty * ViviFrail-based exercise