Malignant tumors,known as chronic wasting diseases,have a high risk of malnutrition.8%to 40%of cancer patients lose 10%or more of their weight.Malnutrition in digestive system cancer(28%−75%)is more common and more serious than in non-digestive system cancer(8%-46.9%)[1].The nutritional indexes such as BMI,Hb,ALB,PA,et al.of digestive system cancer patients are lower than those of non-digestive system cancer patients.Malnourished tumor patients have poor wound healing,prolonged hospital stay,increased cost,mortality and the incidence of complications[2].However,some studies have found that increased nutrition of tumor patients will promote the proliferation and spread of cancer cells and increase the chance of metastasis,which puts the nutritional treatment of tumors in a dilemma.Should cancer patients be treated with nutrition?