Gastric cancer ranks among the top ten leading causes of death in Taiwan. Radical surgery is the sole curative method for gastric cancer. However, our previous research has revealed that elderly gastric cancer patients undergoing radical surgery face a significantly elevated risk of postoperative complications. Even after gastric cancer resection, only 70% of patients receive adjuvant chemotherapy, with a particularly low likelihood among those aged ≥ 65 to undergo such treatment. With the increasing elderly population in our country, an increasing number of elderly gastric cancer patients must decide whether they can withstand radical surgery for gastric cancer and whether to undergo adjuvant chemotherapy. Therefore, increasing the rates of elderly gastric cancer patients undergoing radical surgery and adjuvant chemotherapy, as well as improving the success rate of chemotherapy, has become a critical issue. Frailty has been a frequent topic in geriatric medicine in recent years. It involves assessing multifaceted aspects of physical functioning to determine an individual's frailty status, which can help predict the likelihood of severe side effects from medical interventions. International organizations like the American Cancer Society recommend frailty assessment for all elderly cancer patients before undergoing chemotherapy and corresponding interventions to address frailty. However, there is a lack of large-scale studies on frailty assessment and its practical clinical benefits in our population. This study is a prospective, open-label, randomized clinical trial designed to investigate the impact of geriatric intervention on the tolerance of surgery/chemotherapy in patients diagnosed with gastric cancer. As part of the study protocol, all enrolled patients will undergo a comprehensive frailty assessment within a window of 7 days before initiating their first treatment, followed by tailored geriatric interventions. The primary objective of this study is to assess and compare the effects of geriatric intervention on postoperative complications, chemotherapy tolerance, treatment-related toxicity, and overall quality of life among two distinct groups: frail and non-frail patients. Our research team aims to promote widespread frailty assessment and interventions with the following objectives: 1. Reduce the probability of postoperative complications among elderly gastric cancer patients receiving surgery. 2. Enhance the tolerance and success rate of adjuvant chemotherapy for gastric cancer. These efforts ultimately aim to improve the survival prognosis of this patient group.