In the eyes of the general public, malignant tumor is a disease of adults. For children, malignant tumors are not well understood and not enough attention is paid to them. In fact, in modern society, malignant tumor is a common disease in children, which not only affects their growth and development, but also endangers their lives. According to the data, there are more than 300 million children in China, and about 30,000 children are diagnosed with malignant tumors every year, among which about 20,000 are solid tumors. The most common malignant tumor in children is leukemia, which accounts for about 30% of all cases. The second most common tumor is central nervous system tumor, accounting for about 20% of all cases. This is followed by lymphoma, which accounts for about 10% of cases. In recent years, with the decrease in the mortality rate of infectious diseases and the increase in the cure rate of congenital malformations, malignant tumors have become the leading cause of death in children, ranking second only to accidental death. Etiology of childhood malignant tumors The exact etiology of childhood malignant tumors is still unclear, but it can be determined as a result of congenital or acquired multifactorial effects. Some malignant tumors are related to congenital factors such as fetal genetic defects or intrauterine infection with microorganisms such as viruses and bacteria, exposure to radiation or drugs, while others are related to exposure to toxic substances (such as paints and other chemicals), exposure to radiation (such as extensive exposure to X-rays, natural stones containing radiation such as marble for home decoration) and infection with specific microorganisms. Recent studies have found that second-hand smoke and obesity are also associated with malignant tumors in children. The latest information on tumor epidemiology at home and abroad indicates that the occurrence of tumors in children may be related to parents’ occupation. According to the survey, the fathers of children with leukemia are mostly drivers, automatic mechanics, pharmacists, paint workers and workers in the rubber and plastic processing industries, who are often exposed to ionizing radiation and certain chemical substances (such as benzene, etc.). Mothers of children with acute lymphoblastic leukemia are often exposed to pesticides, hydrocarbons, dyes, and gasoline during pregnancy. Fathers of children with neurological tumors are mostly workers in printing, painting, electrical appliances, smelting, etc. They are often exposed to dyes, pigments, metals, electromagnetic radiation, ionizing rays, and mothers of children with neurological tumors are mostly exposed to chemical substances in their working environment. Characteristics of malignant tumors in children Prevalent sites: Malignant tumors in children tend to occur in the hematopoietic system, central nervous and sympathetic nervous systems, soft tissues, bone and kidney, such as leukemia, malignant lymphoma, neuroblastoma, retinoblastoma, malignant teratoma, rhabdomyosarcoma, nephroblastoma and osteosarcoma. Age of onset: The peak incidence of embryonal malignancies such as nephroblastoma, neuroblastoma, embryonal tumor, hepatoblastoma and malignant teratoma is usually between 1 and 3 years old. The incidence rate decreases year by year as the age increases. The peak incidence of osteosarcoma, lymphoma, thyroid cancer and gastrointestinal adenocarcinoma is in older children, especially in adolescence. Clinical manifestations: Because children are growing and developing, and the embryonic tissues of tumors themselves have developmental characteristics, pediatric malignant tumors grow rapidly. Most malignant solid tumors are noticed by parents because of painless lumps that grow rapidly in a short period of time, such as enlarged lymph nodes in the neck and abdominal lumps. Some abdominal tumors cause abdominal pain, intestinal obstruction, blood in stool, jaundice and other symptoms in children before they are detected by doctors. Many tumors invade or metastasize to adjacent tissues, or lymph nodes, or metastasize to lung, liver, bone or brain via blood transport at an early stage. Treatment of children’s malignant tumors Early detection Because of the insidious clinical manifestations of children’s malignant tumors and the young age of children cannot express them, as a result, many children are already in the middle and late stages when they are diagnosed with tumors, which delays the best time for treatment and causes serious consequences. In daily life, parents should be highly alert to some abnormal reactions and symptoms of children, such as long-term low fever, emaciation, weakness, pallor and decreased appetite; symptoms of endocrine disorders, such as disproportionate obesity or precocious puberty; local pain and lumps as well as a series of symptoms arising from the pressure of hidden lumps on surrounding organs, such as difficulty in breathing or breath-holding, nausea and vomiting, difficulty in defecation or urination and blood in stool. It is suggested that parents should master some scientific knowledge about children’s tumors, observe children’s physical condition carefully, do regular health checkups for children, and go to regular children’s specialized hospitals in time once abnormalities are found. Early treatment Except for hematologic malignancies (leukemia, lymphoma, etc.), the treatment of childhood malignancies is still a comprehensive treatment mainly based on surgery, including preoperative and postoperative chemotherapy and radiotherapy, as well as other local or systemic treatments, including immunotherapy, differentiation inducers, anti-tumor angiogenic agents. In recent years, neoadjuvant chemotherapy has been administered preoperatively to children with intermediate and advanced stages, so that tumors that are too large or invade major organs and blood vessels, as well as tumors that are difficult to be completely resected in one stage can be successfully and safely resected after shrinking, and the metastasis and recurrence of tumors after surgery can be effectively controlled, which effectively improves the cure rate of advanced tumors. For example, the 5-year survival rate of renal embryoma has increased from 30% to 85% in the 1960s, neuroblastoma from 25% to 50%, Hodgkin’s lymphoma from 25% to 60%, and the early remission rate of childhood leukemia is over 95%, and the long-term remission rate is over 70%. After cured, children can grow up to be adults and study, work and live like normal people, so once the tumor is diagnosed, the earlier the treatment, the better the effect. Prevention of childhood malignant tumors Because childhood malignant tumors have insidious onset, rapid progress, high malignancy and early metastasis, the treatment effect of many tumors is still unsatisfactory. Therefore, while emphasizing early detection and treatment, the public should also be reminded to pay attention to prevention and avoid exposure to carcinogenic and teratogenic substances. Pregnant women should avoid exposure to toxic and harmful substances during pregnancy, especially in the early stage (within 3 months). Modern home decoration materials vary, and many of them contain toxic substances or rays, and new furniture and paints and other chemicals have an impact on the fetus. At least 3 months of ventilation after the house decoration before moving in. Pregnant women should pay attention to avoid upper respiratory tract infections or oral antibiotics in the early stages of pregnancy, and prohibit exposure to X-rays. Studies have found that 25-30% of tumors are related to food, because heavy metal elements such as aflatoxin, nitrosamines and lead in food, residual fertilizers and pesticides in vegetables and fruits, additives and preservatives in certain foods are all “invisible killers”. Children should avoid contact with toxic and harmful substances in life, do not eat moldy, expired, no quality assurance of food. Nowadays, there are harmful food additives such as gutter oil, Sudan red and toxic hot pot base in some areas of the market, parents should be vigilant and pay attention to identification.