perioperative multimodal rehabilitation program with telephone supervision

The goal of this clinical trial is to investigate the effects of a perioperative multimodal rehabilitation program on the incidence of postoperative complications and perioperative clinical indexes including functional capacity, nutritional and psychological status in patients with gastric cancer undergoing neoadjuvant therapy. Besides the investigators also develop a smart phone based digital platform aiming to evaluate its effectiveness in improving patient adherence, compared with the conventional telephone supervision approach. The main questions it aims to answer are: * Can the perioperative multimodal rehabilitation program reduce postoperative complications in patients with gastric cancer undergoing neoadjuvant therapy? * Can the smart phone based digital platform improve patients' adherence compared to traditional telephone supervision? * Can the perioperative multimodal rehabilitation program improve the perioperative clinical indicators of patients with gastric cancer undergoing neoadjuvant therapy, including functional capacity, nutritional status and psychological condition? The investigators will compare the perioperative multimodal rehabilitation program with the standard treatment alone to determine whether this program has the effects mentioned above. Participants will follow the perioperative multimodal rehabilitation program from neoadjuvant therapy through to four weeks after discharge.