Due to fasting after surgery, eating disorder during radiotherapy and consumption of tumor itself, malignant tumor patients often have different degrees of malnutrition. We often encounter patients or their families asking about diet and find that there are several wrong views as follows: 1. Some patients take it for granted that the better they eat, the more nutrition the tumor will get and the faster it will grow, while less food can starve the tumor cells to death. This view is not based on science. In fact, this “starvation therapy” can lead to malnutrition and aggravate the disease of the patient, which will also make radiotherapy and chemotherapy not carry on well, which is extremely unfavorable to the treatment. 2. Enthusiasm for dietary prescriptions. There are hundreds of folk dietary prescriptions for cancer treatment and countless ancestral secret prescriptions, and there is no shortage of enthusiastic friends and relatives introducing certain magical anti-cancer doctors around tumor patients. Some foods do have anti-cancer effects, but their anti-cancer effects must not be exaggerated. Compared with chemotherapy drugs, their anti-cancer effects are worlds apart. 3.The saying of “hairy food”. The folk term “hairy substances” refers to certain foods that can induce the occurrence or aggravation of certain diseases, such as some foods related to allergic diseases that can induce asthma and hives. In fact, whether tumor patients need to avoid eating or not should be determined according to their own condition and whether they are combined with diseases related to certain “hairy substances”. An obvious example is that many patients and family members think that seafood is a “hairy food”, which conflicts with surgery, radiotherapy and other treatments and should not be consumed. In fact, some people do have allergic reactions to certain sea and river food, but from a nutritional point of view, seafood is rich in protein and highly nutritious to the human body, so as long as there is no previous adverse reaction to it, it is safe to eat.