Many patients diagnosed with malignant tumors and their families often ask me the question, is this disease hereditary? I think this is not a question that can be explained in one sentence or a few sentences. With the development of molecular biology and molecular genetics, scientists have gradually gained some understanding of the development of tumors. Here are some understandings on epidemiology, basic and clinical research of tumors in recent years to share with you. 1. Epidemiological studies show that the occurrence of some tumors is related to race, and the incidence of certain tumors has significant differences in different races. For example, the incidence rate of nasopharyngeal cancer among Chinese, Malays and Indians in Singapore is 13.3:3:0.4. The incidence rate of nasopharyngeal cancer among Chinese immigrants to the United States is also 34 times higher than that of white Americans. Some other tumors are similar. For example, blacks rarely suffer from Ewing’s osteoma, testicular cancer, and skin cancer; Japanese women have less breast cancer than whites, but more than 10 times more pineal tumors than other ethnic groups. Racial differences are mainly genetic differences, which also prove that genetic factors play an important role in tumor development. Cancer family refers to a family with high incidence of malignant tumors (about 20%), early age of onset, usually inherited in an autosomal dominant manner, and high incidence of certain tumors (e.g. adenocarcinoma), etc. Lynch summarized the above characteristics as “cancer family syndrome”. Lynch summarized these characteristics as “cancer family syndrome”. A cancer family (family G) has been reported, with five investigations over 70 years (starting in 1895), with some clades passed to the seventh generation, and a total of 95 cancer patients among 842 descendants, with the majority suffering from adenocarcinoma of the colon (48) and endometrium (18). Among these 95 patients, 13 had multiple tumors and 19 had cancer before the age of 40; 72 of the 95 patients had one of the two parents with cancer, 47 males and 48 females each, close to 1:1, consistent with autosomal dominant inheritance. For example, 12-25% of colon cancer patients have a family history of bowel cancer. Many common tumors (e.g., breast, bowel, and stomach cancers) are usually disseminated, but a proportion of patients have a significant family history. In addition, the incidence rate among first-degree relatives of patients is usually 3-4 times higher than that of the general population. The mode of inheritance of this type of cancer, although not well understood, suggests the phenomenon of family aggregation of some tumors or the increased susceptibility of family members to these tumors. 3.Some hereditary tumors, at present, it is clear that tumors are hereditary tumors mostly occur in infancy and early childhood, mainly, retinoblastoma, neuroblastoma, nephroblastoma, colonic polyp syndrome and more than 20 kinds. These tumors are caused by the activation of identified oncogenes or deletion of oncogenes, and animal models of such tumors can be simulated in the laboratory by gene integration or knockout. The above surveys and studies actually illustrate that tumors have some genetic predisposition, but it is not the same as tumors are a genetic disease that will be 100% inherited to offspring. Although hereditary tumor is a serious hereditary disease, it only accounts for about 1% of the total tumor incidence, and the majority of tumor history is the result of a combination of environmental and individual genetic susceptibility. A large number of studies have confirmed that the causative factors of most tumors are environmental factors accounting for more than 80%. These include physical (e.g., radiation), chemical (e.g., amphetamines, tobacco) and biological (e.g., viruses, bacteria, toxins) factors. However, only a minority of individuals exposed to carcinogenic substances develop the disease – individual susceptibility factors play an equally important role in the pathogenesis. The genetic basis of this difference is the single nucleotide mutations in genes that cause the metabolism and elimination of environmental carcinogens, the repair of DNA damage, and the timely detection, killing, and elimination of foreign cells, thus determining the individual’s susceptibility to cancer. In this case, what the previous generation inherits to the next generation is not the disease itself, but the susceptibility to the disease. Since cancer is multifactorial and multi-step, susceptibility is also multi-faceted. In the process of cancer transformation, each step of a cell encounters corresponding resistance and repair, and a cell must have gone through a “thousand hardships” to become a cancer cell. In the process of cell cancer, the body has many chances to make a cancerous cell “die”, depending on the effective function of those related genes. If an individual inherits multiple unfavorable susceptibility genes from both parents, he or she will be much more likely to develop cancer than others. At this point, because the role of each gene in cancer susceptibility is minimally effective, susceptibility inheritance is often also characterized by polygenic inheritance – a slight tendency for family aggregation. The genes involved are divided into three areas according to the mode of tumor inheritance: pathogenic genes found in genetic line tumors; tumor susceptibility genes that monitor and prevent multi-step cellular carcinogenesis, and oncogenes and oncogenes that can directly cause disorders of cell proliferation and differentiation. These genes are used for no more than three purposes: (i) to detect carriers in individuals with family history of tumors, to detect positive individuals at an early stage, to prevent treatment, to follow up and monitor, and even to guide eugenics; more than 20 family line tumor-causing genes have been cloned and the forms and patterns of genetic alterations have been studied. When the DNA test of a person with familial tumor does find an abnormality in this gene, it can be used as a genetic marker for the family to test the non-creating individuals in the family. This testing can provide benefits to patients in general, such as close follow-up for early detection and treatment, or even preventive treatment. For example, for familial breast cancer associated with BRCA1, the test kit is widely used abroad. Some patients who are considered carriers will voluntarily opt for prophylactic mastectomy, thus avoiding the risk of breast cancer altogether. (b) Screening the population for individuals at risk using tumor susceptibility genes. Since the majority of tumors are not familial, but are determined by a combination of environmental and susceptibility qualities, screening for susceptibility genes will have greater population coverage and will be important for disease prevention. For high-risk individuals, prevention will be very effective because although they have inherited unfavorable genes, they will not “spontaneously” develop the disease under a healthy environment as hereditary family members do. The use of susceptibility gene testing to predict high-risk groups will strongly promote the development of secondary prevention, thus increasing the proportion of early diagnosis and treatment of tumors. (3) Oncogenetic auxiliary diagnosis The changes of oncogenes and oncogenes in tumor cells can be used as genetic markers of tumor cells for clinical application. When a tumor is pathologically diagnosed, the molecular biology method to detect and understand its multiple genetic alterations will help prognosis, predict metastasis and guide individualized treatment or even gene therapy. Currently, genes that can better assist in diagnosis, prognosis and guide treatment include erbB-2 P53 CD44, etc. Although scientists have discovered and cloned a large number of oncogenes and oncogenes, only a very few of them are actually used in clinical practice, and most of them are in research status. However, it does not prevent people from applying the existing research results to serve the prevention, diagnosis and treatment of cancer. In conclusion, commonly speaking, tumor is a multifactorial and multi-stage development process based on certain genetic susceptibility, with the participation of environmental factors, and environmental factors are the main cause of tumor occurrence. Therefore, even if we cannot screen out the high-risk people by tumor susceptibility gene, some of the tumors can be prevented by adopting good lifestyle and improving environment.