It is crucial to promptly identify nutritional issues in these patients within the community and provide them with dietary guidance, nutritional counseling, and support. This study will be conducted in communities in Chengdu, Sichuan. Community management teams will register oncology patients, collecting information such as demographic data, tumor type, stage, specific treatment plan, treatment hospital, regularity of hospital admissions, and frequency of independent smartphone use. Registered patients will be screened based on inclusion and exclusion criteria. For those who meet the criteria, the community management team will contact them and recommend the use of a dedicated app developed by the research team. An initial nutritional assessment will also be conducted. Patients identified with nutritional risks will be directly referred to the research team's clinical nutritionists for face-to-face consultations. After additional tests, such as body composition analysis, necessary nutritional education and stepwise nutritional interventions will be provided. These patients will also use the app for dietary monitoring and nutritional guidance. For patients without nutritional risks, the app will be recommended for daily questionnaire completion and activity tracking.