肿瘤患者营养不良和恶液质发生率极高。营养不良可能引起患者治疗耐受性下降，治疗机会减少，并发症增加， 发病率和死亡率增加，住院时间延长，生存期缩短。这些不仅严重影响治疗效果、降低患者生活质量，还造成了巨大的经济损失和社会医疗资源的浪费。营养治疗作为临床治疗及康复的基础手段之一，国内外大量循证医学证据表明，合理、有效地提供营养支持，并不会增加肿瘤复发率或转移率、降低生存率，反而可明显提高肿瘤患者术后营养和免疫状况，减少术后并发症和感染的发生，提高患者救治率、降低病死率，降低药占比及医疗支出，对大部分营养不良肿瘤患者具有积极意义。为了更好地将肿瘤的医学营养治疗理论落实到临床实践，本共识根据国内外现有研究证据，从肿瘤与营养的关系出发，并结合我国膳食现状和特点，对该领域的研究结果进行系统总结，逐一分析膳食营养因素对肿瘤患者的影响，规范肿瘤医学营养治疗原则和步骤，以便临床医师、临床营养专业人员、护士等医疗保健人员应用，更好地为肿瘤患者服务。

Malnutrition and dyscrasia are very common in cancer patients. Malnutrition is associated with poor treatment tolerance, reduced opportunities for treatment, increased complications, increased morbidity and mortality, prolonged hospital stay, and lower survival rate. Malnutrition not only has an impact on the effect of treatment and quality of life, but also cause huge economic losses and waste of social medical resources. Nutrition therapy as a basic methods of clinical treatment and rehabilitation, has been proved by a large number of evidence-based medicine at home and abroad. The evidence shows that the reasonable and effective nutritional support will not increase the rate of tumor recurrence or metastasis rate and lower survival rate, but can significantly improve the postoperative cancer patients nutrition and immune status, reduce the incidence of complications and postoperative infection, improve the cure rate of patients, reduce the mortality rate, reduce drug and medical expenditure, has a positive for most malnourished cancer patients. In order to apply the medical nutrition therapy on patients with cancer to clinical practice, the consensus based on existing research on the relationship between cancer and nutrition at home and abroad, and combined with the status and characteristics of China's diet. Systematically summarize and analyze the influence of dietary nutritional factors on cancer patients and standardize the principles and steps of oncology nutrition treatment. Apply to clinician, clinical nutrition professionals, nurse, and other health care workers.