The role of dietary factors in tumorigenesis A large amount of research data show that: about 35% of cancers are mainly related to frequent smoking and drinking too much strong alcohol, including some lung cancers, oral cavity cancers, esophageal cancers, laryngeal cancers, as well as some bladder cancers; about 45% of cancers are related to nutritional factors, which refers to the dietary intake of calories, fat (saturated and unsaturated cholesterol, fats) is too much, and some nutrients (e.g. vitamin A, food fiber, etc.) are insufficient in the food. This refers to excessive dietary intake of calories and fat (saturated and unsaturated cholesterol and fat), and insufficient of certain nutrients in food (e.g. vitamin A, dietary fiber, etc.). Cancers belonging to this category include stomach, rectum, colon, ovary, uterus, and breast cancers, and some people refer to cancers caused by these reasons as “lifestyle cancers”. It is expected that 1/3 of cancers can be reduced by rationalization of diet, and 1/3 of cancers can be reduced by reducing smoking and drinking alcohol. Human beings have not yet fully understood the causes of tumors, but the popular view is that the occurrence of tumors is due to both genetic and environmental causes. Genetic factors mainly affect the sensitivity of the organism to environmental factors. According to the research of American scientists, the main environmental factors and their weights in tumorigenesis are as follows: ① smoking accounts for 30%; ② dietary factors account for an average of 35% with a variation of 10% to 70%; ③ fertility and sexual behavior accounts for 7%; ④ occupational factors account for 4%; ⑤ alcohol abuse accounts for 3%; ⑥ geographic factors account for 3%; ⑦ environmental and water pollution accounts for 2%; ⑧ drugs and medical factors account for 1%. The results of many epidemiological investigations also suggest that the occurrence of tumors is related to dietary habits. It can be seen that dietary factors play a very important role in the occurrence of human tumors. Cancer occurs and develops in three main periods, the initiation period, the cancer-promoting period and the malignant progression period. The first two periods are the benign stage of tumor growth, and the lesions in this period can be reversed. Improper dietary nutrition mainly affects the tumor in these two periods, so a good diet can avoid the development to the third stage. Good dietary nutrition not only has the potential role of preventing tumors, but also has the functions of antioxidant, inhibiting the proliferation of tumor cells, stimulating the body to produce interferon, and so on, and therefore also plays a positive therapeutic role to a certain extent. Nutritional therapy and anti-tumor therapy have the same important status Currently, the main treatment for tumors is surgery, chemotherapy and radiation therapy. It is found that increasing nutrition of cancer patients will promote the growth and proliferation of cancer cells and increase the chances of metastasis, which puts nutritional treatment of tumors in a dilemma, but after repeated weighing, nutritional treatment is still an important aspect of tumor treatment, and it is the basis of other treatments. At present, under the reality that our country generally pays attention to other treatment methods and belittles nutritional therapy, nutritional therapy and anti-tumor therapy for tumor patients should be put in the same important position. Tumor cells are a kind of rapidly expanding and growing cells, which need a large amount of nutrients. Tumor cells are bound to compete with normal tissues for nutrients, and normal cells will always be the losers in this battle, so without nutritional therapy, the damaged ones are often normal cells, tissues and organs in the first place. Cancer patients, like normal people, will suffer from malnutrition if nutrition is not increased, which will reduce the immunity of the body and seriously affect the recovery of the patients. Therefore, it is beneficial for cancer patients to cooperate with high nutrition during treatment. Nutritional therapy benefits the organism more than the tumor. Foreign countries have taken nutrition therapy as an important part of the whole anti-cancer program. Appropriate nutritional therapy can not only improve the nutritional status of patients, make their immunity and anti-cancer ability strengthened and improve the quality of life, but also improve the tolerance of tumor patients to surgical treatment, reduce or avoid post-surgical infections, make post-surgical wounds heal as scheduled, improve the tolerance of tumor patients to radiotherapy or chemotherapy, and alleviate their toxic side effects. Our people pay more attention to the role of traditional Chinese medicine and nutritional supplements, in fact, there is no exact evidence to prove that nutrients directly have a killing effect on tumor cells, and their main role is to enhance the physical and immune functions, to achieve the role of the body’s immune system to inhibit the growth of tumors. When choosing supplements, the following points should be grasped: (1) Diet should be put in the first place, and supplements are secondary; (2) It is not advisable to “make up”. The use of several kinds of supplements together, or the use of daily large doses, not only can’t play a good role, but also lead to the opposite effect; (3) Don’t believe that there is a kind of supplements have the role of treating tumors. They are always auxiliary means of treatment. Various kinds of tumors and their treatment means will affect the nutritional status of patients. Malnutrition is common among tumor patients. The main nutritional problems of tumor patients are: 1. Anorexia and weight loss: it can be seen in various tumors or patients treated with surgery, radiotherapy and other drugs. Anorexia is most common in digestive tract tumors, especially esophageal cancer, gastric cancer and colorectal cancer. Metabolic abnormality of tumor patients: energy metabolism is increased, and it is generally believed that energy metabolism of tumor patients is 10% higher than normal, weight loss is a common phenomenon in tumor patients, which may be caused by decreased intake due to decreased appetite on one hand, or caused by increased consumption on the other hand; carbohydrate metabolic abnormality is mainly caused by glucose intolerance in many tumor patients; protein metabolic abnormality is manifested in increased conversion rate of protein, protein synthesis by liver, and increased conversion rate of protein in the liver. Abnormalities in carbohydrate metabolism are mainly caused by glucose intolerance in many tumor patients; abnormalities in protein metabolism are manifested in increased protein conversion rate, increased protein synthesis in liver, decreased protein synthesis in muscle and decreased plasma branched-chain amino acids; fat metabolism is manifested in enhanced lipolysis, decreased activity of serum lipoprotein lipase, and hyperlipidemia; vitamin metabolism is mainly manifested in decreased antioxidant vitamins, such as vitamin C, vitamin E, and so on; and decreased content of selenium and zinc in blood of patients with tumor can be seen in trace element metabolism. Nutritional therapy for tumor patients (I) Judgment and typing of malnutrition Malnutrition in tumor patients is a vicious circle, due to loss of appetite, reduced intake, resulting in reduced physical activity, generalized weakness, decreased digestion and absorption function, further resulting in anorexia, which ultimately leads to weight loss, generalized failure, and affects the prognosis. Malnutrition can be divided into three categories: ① wasting malnutrition: mainly caused by insufficient caloric intake of muscle tissue and subcutaneous fat consumption, characterized by a decline in body weight and other anthropometric values, while serum proteins remain normal. ② protein malnutrition: mainly caused by insufficient protein intake or excessive loss, while the food intake is normal or more, characterized by visceral protein storage depletion. The main manifestations of serum albumin, transferrin, prealbumin and other concentrations of reduced immune function is impaired, while the anthropometric indicators are still normal or even higher than normal. Mixed malnutrition: caused by insufficient intake of protein and calories, manifested by hypoproteinemia, and all anthropometric indicators are lower than normal. This type is the most serious type of malnutrition, with decreased skeletal muscle and visceral protein, empty endogenous fat and protein reserves, impaired organ function, high incidence of infection and other complications, and poor prognosis. (II) Purpose of tumor nutritional therapy 1. Correct or improve the nutritional status of patients, improve the immune function and disease-resisting and cancer-resisting ability of the body, so as to achieve the purpose of “supporting the positive and counteracting the evil”. 2. 2.To improve the quality of life by adjusting the nutritional status of patients, to avoid anxiety, and to make the patients full and happy in spirit and psychology. 3. Nutritional therapy is an indispensable part of the total treatment program for cancer patients. Nutritional therapy can improve patients’ tolerance to surgical treatment, reduce postoperative infection, accelerate wound healing, improve patients’ ability to tolerate chemotherapy and radiotherapy, and reduce the toxicity and side effects of treatment. (III) Daily nutritional support for tumor patients 1. Nutritional requirements of tumor patients include two parts, i.e. daily basic nutritional requirements and increased nutritional requirements due to tumor growth, infection, anemia and treatment, so the supply of various nutrients should be higher than the recommended amount, especially the amount of animal protein. 2, dairy products: including various forms of dairy products. This type of food is the main source of vitamins A, B and D, as well as calcium, can also provide a certain amount of protein. 3. Vegetables and fruits: mainly provide vitamins and minerals, especially citrus glutinosa is the main source of vitamin C. Dark yellow-green vegetables can provide carotene. (D) Nutritional support for surgical patients Surgery is a common method to treat tumors, but at the same time, it must be recognized that surgery brings trauma to the organism while treating diseases. Improving the nutritional status of the body before surgery can increase the body’s resistance and tolerance to surgery, reduce postoperative complications and infections, and promote wound healing. Effective postoperative nutritional supply has a positive effect on the early recovery of the organism. Nutritional supplementation before surgery can improve immunity also promote tumor growth. Research of Shanghai Ruijin Hospital showed that: preoperative nutritional support for gastric cancer patients, supplementation of energy and amino acid for 1 week. increased NK cell activity, increased CD4, CD8, increased tumor cell iso-ploidy, increased DNA content, increased percentage of S-phase, and increased percentage of proliferating cells. For non-gastrointestinal surgery pre-surgical patients diet is based on low fat, high protein, high vitamins and minerals. Choose fish, chicken, eggs, milk, soy products rich in high quality protein and fresh fruits and vegetables rich in vitamins and minerals. Patients undergoing gastrointestinal surgery are given a semi-liquid diet with little residue from 2 to 3 days before surgery. A liquid diet is given the day before surgery or an elemental diet is given starting 5 days before surgery. After the patient’s surgery, when the patient can eat, the amount of diet can be gradually increased according to the physical condition, and gradually transition from liquid to semi-liquid, soft food and general food. (E) Nutritional support for chemotherapy tumor patients Chemotherapy is an effective means of tumor treatment, but almost all chemotherapeutic drugs will cause patients with different degrees of loss of appetite, nausea, vomiting, etc., thus affecting the nutritional status of patients. A proper diet can prevent and minimize weight loss and malnutrition brought about by treatment. Studies have found that certain antioxidant nutrients can reduce the adverse effects caused by chemotherapy, so more antioxidant nutrients should be supplemented, such as vitamin A, vitamin C, vitamin E, ß-carotene, and foods rich in trace elements zinc and selenium. It is found that various nutrients can reach maximum blood concentration 24 hours after supplementation, so 24 hours after supplementation is the most suitable period for chemotherapy. Dietary nutrition of chemotherapy patients should be directed to the adverse reactions of chemotherapy. The side effects of chemotherapy are mainly manifested in systemic reactions, digestive reactions, bone marrow suppression and other aspects. The diet of chemotherapy patients should be light, rich in nutrients and easy to digest, and they can eat semi-fluid or soft rice with little residue, avoiding greasy and indigestible food. In order to prevent or reduce the decline of white blood cells and platelets caused by bone marrow suppression, it is advisable to eat more blood and meat, etc. Cooking methods such as boiling, stewing and steaming are preferred, and foods containing more iron, such as animal offal, egg yolks and lean meats, etc., can be chosen to correct the iron-deficiency anemia of patients with tumors. Mushrooms such as shiitake, mushroom, monkey head mushroom and fungus have been found to be rich in polysaccharides, which are very effective in improving cellular immune function of human body. (F) radiotherapy patients dietary nutrition patients during treatment often appear dry mouth, sore throat, nausea and anorexia. Nasopharyngeal dryness, yellow urine and low urine and other symptoms, especially malignant tumors of the maxillofacial or pharyngeal region, radiotherapy response is heavier, but also can cause oral cavity, pharynx, esophagus and other places of radioactive inflammation. Therefore, we should deal with the dietary problems according to the different clinical symptoms. For those who have severe reaction to radiotherapy, poor appetite, painful swallowing and ulcers in the mouth, semi-fluid diet or tube-feeding nutritional support is preferred. In order to stimulate appetite, a little more salt can be put in to ease the feeling of lack of taste in the mouth, meat can be scratched or stewed, and vegetables or fruits can be juiced if they cannot be swallowed. Avoid dog meat, mutton, onion, ginger and other hot foods and spicy stimulating foods. Patients with head and neck radiotherapy should eat more soupy, thin, soft and list foods. If swallowing is difficult, you can eat some cold food to ease. Drink plenty of water. For patients with abdominal radiotherapy, the diet should be fine and soft, and choose more easily digestible food. Drink plenty of water and eat small, frequent meals. Eat less milk, sweets and honey to prevent intestinal discomfort. After radiotherapy, it is advisable to choose a high protein, high calorie diet to replenish the energy lost due to treatment. Choose lean meat, chicken, fish, eggs, tofu and other foods rich in high quality protein. If the tumor patients are in serious condition after surgery, the natural diet can not solve the patient’s problems, the nutritional support therapy commonly used in surgery must be used. The purpose of nutritional support therapy is to prevent and correct malnutrition that may occur or has already occurred in the patient’s disease and treatment. Nutritional support therapy includes both enteral and parenteral methods. Enteral nutrition (enteral nutrition) consists of providing nutrients needed for the body’s metabolism through the mouth and feeding tube. Parenteral nutrition (PN) refers to the provision of complete and adequate nutrients through the intravenous route for the purpose of maintaining the body’s metabolic needs. When the patient is fasted and all nutrients are provided through the intravenous route, it is called total parenteral nutrition (TPN). (Tube feeding therapy is characterized by its conformity to human physiology, convenient operation and low cost; it maintains the integrity of intestinal mucosal structure and barrier function; and it is the first choice for nutritional support. The preparations used in tube feeding nutrition include two kinds, namely, homogenized diet and elemental diet. A homogenized meal is a nutritional solution of a variety of natural foods that are often consumed, crushed and processed and mixed into a fluid. Indications for homogenized diet: gastrointestinal tract with digestion, absorption function, but can not be oral diet of patients; homogenized diet contraindications mainly include gastric retention or intestinal obstruction digestive tract activities bleeding intestinal infections, severe diarrhea shock. Physicochemical properties of homogenized diet: the composition is close to the dietary structure of normal people, with a natural flavor; can be prepared by themselves, the nutrient content is difficult to calculate accurately; limited by the type of food, the nutrient content is not comprehensive. Elemental diet is a kind of comprehensive nutrients, chemical composition is clear, without digestion that can be directly absorbed and utilized by the intestinal tract without residue diet. Elements of the composition of the meal is based on the body’s daily dietary nutrient requirements and recommended amount based on hydrolyzed protein, carbohydrate, fat and micronutrients formulated; elements of the meal is characterized by a clear chemical composition, precise content; without digestion; easy to dissolve; calories 1kcal / ml; osmolality, high, weakly acidic; does not contain lactose; palatability is poor, it is not suitable for oral intake. (II) Parenteral nutrition Provide complete and sufficient nutrients through the intravenous route to maintain the body’s metabolic needs. When the patient is fasted and all nutrients are provided through the intravenous route, it is total parenteral nutrition (TPN). Indications for parenteral nutrition are protein-calorie malnutrition, gastrointestinal dysfunction, acute pancreatitis, intestinal obstruction, intestinal fistula, short bowel syndrome, inflammatory bowel disease, hypercatabolic state, perioperative period, during antitumor therapy, low birth weight infants, and those who cannot eat for more than 7 days. Contraindications to parenteral nutrition include severe water-electrolyte, acid-base imbalance, and shock. The preparation of parenteral nutrition usually has professional manufacturers, can not be prepared by themselves, can provide the body’s daily nutrient needs. VI. Common symptoms affecting nutritional therapy and their treatment measures As many symptoms arising from tumor and tumor therapy will affect the dietary nutritional intake of patients, the adverse effects of these symptoms can be alleviated by dietary and pharmacological means. 1. Anorexia: it is one of the most common symptoms in tumor and tumor therapy. In order to reduce anorexia, psychological and food processing methods should be improved. Dullness of taste: Small and frequent meals, eating more fresh fruits and vegetables, increasing the color and aroma of food, and avoiding certain protein foods that may cause off-flavors may partially overcome the adverse effects of dullness of taste. 3.Dry mouth: it appears after head and neck radiotherapy, due to the decrease of salivary gland secretion. Juicy diet and fruits can be increased, chewing sugar-free gum, sour and spicy foods should be used with caution. 4, dysphagia: often a complication of head and neck radiotherapy or oral surgery, if the symptoms are not serious, can be used to enter the soft food, but do not advocate into the fluid in order to avoid food sucked into the respiratory tract. If the symptoms are serious, tube feeding or intravenous nutrition is needed. 5, bloating: is due to the gastrointestinal tract digestive ability and food through the time prolonged due to, but also with the nature of the food into. Small amount of meals. Sit up or walk properly before and after meals, avoid eating fatty, fried, gas-producing foods, as well as milk and carbonated beverages. 6, constipation: can be due to lack of dietary fiber, reduced activity and the use of narcotic drugs. Diets should be increased with fresh vegetables, fruits, whole grain breads and cereals, and the amount of fluid intake should also be increased, and light laxatives or enemas can be used if necessary. 7, diarrhea: can be due to chemotherapy, abdominal radiotherapy or intestinal surgery. At the beginning, only take liquids to make the intestinal tract rest, and gradually increase the amount of non-slag or less-slag food, and then transition to low-slag soft food and then to normal diet. Avoid eating greasy, spicy, stimulating, too cold and fiber-containing foods. If necessary, drugs can be used. 8, esophagitis: caused by chemotherapy or head and neck radiotherapy. Often cause swallowing pain and difficulty. Gargling or swallowing pain relieving liquid such as lidocaine can relieve pain and irritation, which can help to ease the irritation to esophageal mucosa, and oral antipyretic and analgesic can be taken to relieve pain if necessary. Dietary prevention of tumors Prevention of tumors should pay attention to the following aspects: reduce the intake of carcinogens and carcinogenic precursors in food, such as aflatoxin, fried and deep-fried food, etc.; pay attention to the balance of the intake of the dietary structure, balanced diet refers to the human body’s intake of dietary nutrients of various kinds of complete, sufficient number of dietary nutrients in a reasonable proportion of the nutrient ratio; increase the intake of protective substances such as nutrients, antioxidant nutrients, dietary nutrients, dietary supplements, dietary supplements, dietary supplements, dietary supplementation, etc.; increase the intake of protective substances, such as Antioxidant nutrients, dietary fiber, protein and calcium, as well as antipathogenic foods such as garlic, leeks, etc. and improve immune function of food such as fungal food intake. The National Cancer Institute of Japan has drawn up 12 pieces of advice, which are introduced here. For reference in daily life: (1) Diet should pay attention to both taste and nutrition. (2) Overcome picky eating and partiality, and do not take the same medicine for a long time. (3) Delicious food is not excessive, so that the diet is moderate. (4) Do not drink strong alcohol, but also to avoid drinking too much alcohol. (5) Do not smoke, smokers should quit smoking. (6) Moderate intake of vitamins A, C, E and dietary fiber. (7) Pay attention to eating less oversalted or overheated food. (8) Do not eat burnt food, especially burnt fish and meat. (9) Do not eat moldy food. (10) Avoid excessive exposure to sunlight. (11) Abstain from sex and avoid overwork. (12) Maintain air circulation in the room, pay attention to the body clean. If you can listen to these 12 pieces of advice, then the threat of cancer will undoubtedly be greatly reduced.