Malnutrition is a common comorbidity and complication in cancer patients undergoing radiotherapy. It can reduce the efficacy of radiotherapy increase adverse reactions to radiotherapy and even impact the patient 's survival time and quality of life. Nutritional therapy is crucial for cancer patients undergoing radiotherapy and it is of great significance to provide standardized and effective nutritional treatment for these patients. Nutritional therapy for cancer should be considered as first line and fundamental treatment integrated throughout the entire process of cancer treatment. It is essential for cancer patients to undergo comprehensive nutritional management throughout the "peri-radiotherapy period". Cancer is a metabolic disease and in addition to providing basic nutritional therapy to meet the basic energy protein and nutrient needs of cancer patients personalized and precise nutritional therapy should also actively explore aspects such as dietary regulation targeting tumor metabolism and immunonutrition. Cancer nutritional therapy is not only about supplementing energy and nutrients but also about regulating cancer metabolism and immunity and even improving survival rates. Both basic nutrition and precise nutritional therapy should be emphasized. Furthermore cancer patients endure various psychological and physiological impacts during their treatment. Multimodal integrated rehabilitation can synergistically enhance the patients' recovery making clinical rehabilitation integrated. Research is urgently needed to further explore the clinical application of multimodal integrated rehabilitation based on nutritional therapy in radiotherapy patients through large-scale randomized controlled trials.