Gastric, biliary and pancreatic cancer are commonly malignancies from gastro- intestinal tract in Taiwan. Because lack of specific symptoms at presentation and effective screening methodology, majority of these patients are diagnosed with metastatic or unresectable disease. Palliative chemotherapy is the good standard of therapy for patients with unresectable gastric, biliary and pancreatic cancer with benefit of prolong survival time and improve quality of life. Although the benefit of palliative chemotherapy seems to be the same for elderly and young cancer patients in clinical study, elderly patients are less frequently treated with chemotherapy or treated with suboptimal dosage. Elderly patients do not receive palliative chemotherapy because concerns of elder age, comorbidity, poor performance, lack of social/economic support and worry about treatment toxicities. The increase in life expectancy of the general population resulted in an increase in the number of elderly patients with cancers referred for palliative chemotherapy. Overtreatment may result in high mortality due to disregard of the aging patients' frailty; on the other hand, under-treatment resulting from over-concern regarding their ability to tolerate treatment, may compromise the survival outcome. Therefore, the appropriately selection of geriatric cancer patients for palliative chemotherapy has to be addressed urgently. Frailty is a progressive decline of physiological reserve leading to multiple functional disability and increases vulnerability to subsequent morbidity and mortality. Frailty is associated with treatment toxicity, chemotherapy tolerance, and survival outcome in clinical oncology. Recent randomized study reported geriatric intervention significantly improved chemotherapy tolerance in elderly patients. Therefore, the American Cancer Association has recommended routine geriatric assessment and intervention in oncogeriatric patients upon providing antitumor treatments. However, the effect of geriatric intervention on chemotherapy tolerance is seldom in Taiwan. This study is an open, randomized, prospective trial to evaluate the effect of geriatric intervention on chemotherapy tolerance in patients with unresectable gastric, biliary, and pancreatic cancer. All patients with receive frailty assessment within 7 days before initiation of first cycle palliative chemotherapy followed by geriatric intervention. The study aim is to compare for chemotherapy tolerance, treatment-related toxicity, and quality of life after completion 3 months chemotherapy treatment course between frail and non-frail patients. This study also aims to explore the effect of geriatric intervention of treatment tolerance, treatment-related toxicity, and quality of life in frail patients with gastric, biliary, and pancreatic cancer receiving palliative chemotherapy.