(A) Incidence and prevalence rate The incidence rate or prevalence rate varies greatly from country to country and from tumor to tumor. According to the data from Global Cancer Statistics 2008, the incidence rate of head and neck malignant tumors is high, ranking 6th among the whole body malignant tumors, among which oral cancer is in 12th place. The incidence rate of oral cancer in most countries ranges from 1 to 10/100,000, with individual countries reaching 15/100,000 or even 30/100,000. In general, the incidence rate in developing countries is higher than that in developed countries, and the geographically high to low order is: Asia, North America, Europe, and South America. It is estimated that the number of cases of malignant tumors of the oral cavity, pharynx and larynx is 500,000 per year worldwide. Smoking, excessive alcohol consumption, poor dietary habits and infections are the risk factors of head and neck malignancies, among which more than 90% are attributed to excessive smoking and alcohol, and betel nut chewing is the main cause of high incidence of oral cancer in individual countries or regions. In China, there is no accurate national information on the incidence or prevalence of oral cancer, so the following data are listed for reference. According to the data from the Epidemiology Department of Shanghai Cancer Institute, the incidence rate of head and neck malignant tumors is 11.8/100,000 for men and 8.4/100,000 for women; the incidence rate of oral cavity and salivary gland cancer is 1.9/100,000 for men and 1.6/100,000 for women. In terms of prevalence, the survey of oral and maxillofacial tumors in Xinjiang Uyghur Autonomous Region was 8.10/100,000; the survey in Guangzhou City showed that the prevalence of oral cancer was 1.06~1.09/100,000. Wang Yan’an, Department of Oral and Maxillofacial-Head and Neck Oncology, Ninth People’s Hospital, Shanghai Jiaotong University School of Medicine The above information shows that the incidence or prevalence of oral and maxillofacial cancer tumors in China is not high, in fact, it is not possible to provide exact statistics yet, but due to the large population in China, the absolute number of patients is not small. （From the world, the proportional rate of oral cancer in Europe, America and South Asia is higher than that of China; many of them are in the top 10 in the ranking of malignant tumors. In India, oral cancer is more than 40% of the malignant tumors in the whole body. From the statistical analysis of pathological data, the statistics of 26 regions and 36 units in China, oral and maxillofacial malignant tumors are 8.2% of the whole body malignant tumors. Among the whole body tumors, the ratio of benign to malignant is about 1:1. Oral and maxillofacial tumors, including cysts and tumor-like lesions, are generally more benign than malignant. For example, in the statistical analysis of 15,983 cases of oral and maxillofacial tumors, cysts and tumor-like lesions in the Department of Pathology of the Ninth People’s Hospital affiliated to Shanghai Jiaotong University School of Medicine in 1990s, malignant tumors accounted for only 32.08% (5,128 cases); benign tumors accounted for 42.95% (6,866 cases); cysts accounted for 20.25% (3,237 cases); and tumor-like lesions accounted for 4.70% (752 cases). (iii) Gender and age Oral and maxillofacial malignant tumors mostly occur in males. The age of oral and maxillofacial malignant tumor is 40-60 years old, while in western countries, it mostly occurs above 60 years old, and the peak value of its incidence is about 10 years older than that of China. However, in the late 70s, especially since the 80s, there is a trend of gradual increase in the age of disease in both western countries and China (except for individual cancer tumors), the main reason of which may be related to the increase of the average life expectancy of the overall population. It should be noted that the incidence of oral cancer has been increasing significantly in women in recent years. In Connecticut, the prevalence of oral cancer in women has increased from 1.2/100,000 in the 1930s to 5.3/100,000 (1985), an increase of about 4.5 times, although the number of oral cancer cases in men has also increased in the same period, but only about 3 times. The statistics of 1751 cases of oral squamous carcinoma in Shanghai Jiaotong University Medical College also showed that the growth rate of female patients was much faster than that of male patients: the ratio of male to female was 2.82:1 between 1960 and 1965, but shrank to 1.70:1 between 1993 and 2002. The second is related to the increased participation in occupations originally performed by men. （Benign tumors of oral and maxillofacial origin are mostly of odontogenic and epithelial origin, such as enamel cell tumors and pleomorphic adenomas, followed by mesenchymal tumors such as tubular tumors and fibromas. The most common malignant tumors in oral and maxillofacial area are of epithelial origin, especially squamous epithelial cell carcinoma, which accounts for more than 80% of oral and maxillofacial malignant tumors (about 90% of oral malignant tumors); followed by adenoidal epithelial carcinoma and undifferentiated carcinoma; sarcomas occur less frequently in oral and maxillofacial area, mainly fibrosarcoma and osteosarcoma. Malignant tumors of lymphatic and hematopoietic origin, such as malignant lymphoma, leukemia, etc., may also first appear in the oral and maxillofacial region, and the former has a rapid growth trend in recent years. （Benign tumors of oral and maxillofacial region are mostly found in the gums, oral mucosa, jaw bone and face. In China, gum cancer was highly prevalent in the 1960s, followed by tongue cancer. At present, they are tongue cancer, buccal mucosa cancer, gum cancer, palate cancer and maxillary sinus cancer in order. The prevalent sites in North America are slightly different, in order of tongue, floor of mouth, gingival, and buccal cancers. Lip cancer, especially skin cancer of the face, is less common. The prevalence of cancer is related to the region, climate, race and living habits.