Compared with malignant tumors in other parts of the body, laryngeal cancer is relatively rare, and its incidence rate is generally comparable to oropharyngeal cancer and thyroid cancer, and only 1/10 of lung cancer. Laryngeal cancer is the 11th most common tumor in men and the second most common tumor of the head and neck. The incidence rate of laryngeal cancer varies according to region, gender and age. Regional differences The three major high incidence areas of laryngeal cancer in the world are Varese in Italy, São Paulo in Brazil and Mumbai in India; the sub-high incidence areas are Warsaw in Poland and parts of France and Spain; the low incidence areas are located in Northern Europe, and the incidence rates in the remaining four countries, except Finland, are very low. Since the 1940s, the incidence of laryngeal cancer has been increasing significantly in many countries. According to Fei Shengzhong et al, the incidence rate in China in the 1970s was 37.7 times higher than that in the 1950s. The current incidence rate in China lacks relevant statistics. According to the statistics of the United States, the incidence rate of laryngeal cancer in men and women has decreased from 12:1 to 5:1 in the past 20 years, and the incidence rate of supraglottic laryngeal cancer in women has increased more. In addition, the age of onset is generally earlier in women than in men, with 41% of laryngeal cancers in women under the age of 55 reported, compared to 25% in men. The rapid increase of laryngeal cancer incidence among women may be related to the increase of smoking and alcohol consumption among women nowadays. 3.Age distribution The age of laryngeal cancer is 40-70 years old, with the highest incidence rate around 60 years old, but the age distribution varies slightly in different regions. The incidence rate of laryngeal cancer in China is highest in the age group of 65 for men and 55 for women. The etiology of laryngeal cancer is unclear and may be related to the following factors: 1. Smoking: The earliest report of laryngeal cancer caused by smoking can be traced back to the 1940s. Currently, a large number of animal experiments and clinical epidemiological studies have confirmed that there is a significant correlation between smoking and laryngeal cancer, which is the main risk factor for laryngeal cancer. Alcohol consumption: Clinical observation and epidemiological findings show that there is a correlation between chronic alcohol intake and laryngeal cancer, among which supraglottis laryngeal cancer is the most closely related. Statistics of 164 male laryngeal cancer patients showed that the average daily alcohol consumption was 65.1±49.9g per person, among which 85.1% of patients drank alcohol daily, while the average daily alcohol consumption of 656 cancer-free control group patients was 29.1±31.1g, and 64.4% of them drank alcohol daily. 3.Viral infection: Some studies found that patients with laryngeal cancer were associated with papillomavirus infection. syrianen (1982) was the first to take the immunohistochemical PAS method to detect HPV-Ag in laryngeal cancer, and the positive rate was 36.1%; Loning et al. found the presence of HPV-DNA in 22 cases of oral, pharyngeal and laryngeal squamous cell carcinoma tissues in 8 cases, but not in normal mucosa; and Abramson used molecular hybridization technique to detect HPV16 DNA homologous sequence in 5 cases of laryngeal verrucous carcinoma, and the results were all positive. 4, environmental factors: a variety of environmental factors including inhalation of hot steam, heat damage and various organic compounds (polycyclic aromatic hydrocarbons, formaldehyde) produced in coal mines, steel plants, rubber industries, a variety of fibrous dust, nickel, chromate and asbestos produced in dye and leather manufacturing industries. Currently, the carcinogenic effects of asbestos and mustard gas are largely confirmed. Masgan reported that the relative risk of laryngeal cancer in asbestos-exposed compared to non-exposed individuals was nine times greater in the former than in the latter. Mustard gas is also considered to have a strong correlation with laryngeal carcinogenesis. 5.Ionizing radiation: In 1934, VonEichen and Soerusen reported that ionizing radiation induced laryngeal carcinogenesis. Since then, occupational exposure to alpha radiation, therapeutic doses of active iodine and external irradiation have been reported to cause laryngeal cancer. Laryngeal papillomas occurring in adolescence are generally not considered to be cancerous, but malignant changes have been reported in such patients after radiation therapy. Gastroesophageal reflux: Gastroesophageal reflux has received increasing attention from scholars because of its ability to cause esophagitis, Barrett’s chemosis, esophageal cancer and some extraesophageal complications. There is evidence that certain unexplained pharyngitis and subglottic stenosis are associated with it. 7.Laryngeal mucous membrane leukoplakia: laryngeal mucous membrane leukoplakia is a lesion in which the laryngeal mucous membrane appears as a raised white mass or epithelial lamellar hyperplasia showing keratinization. Some of the white spots may become cancerous. It is difficult to distinguish from carcinoma in situ and early invasive carcinoma in appearance. 8.Laryngeal keratosis: laryngeal keratosis can occur in any part of the larynx. 9.Papillary laryngeal tumor: Papillary laryngeal tumor is the most common benign tumor of the larynx, which has the tendency of malignant transformation, with a malignant rate of about 3%. At present, it is believed that laryngeal papilloma is a kind of pre-cancerous lesion of larynx. 10.Chronic proliferative laryngitis: chronic proliferative laryngitis is mostly characterized by irregular epithelial hyperplasia, and there is often extensive chronic inflammatory cell infiltration in the subepithelial layer. This disease has an obvious tendency to malignant transformation.