Pathogenic conditions external factors 1, physical factors: heat, injury, ultraviolet light, X-rays and long-term chronic stimulation (root stumps, sharp tooth tips, bad restorations, etc.), lip cancer is mostly seen in people who smoke cigars and pipes, excessive outdoor ultraviolet radiation can cause lip cancer and skin cancer, radiotherapy can cause radioactive cancer. 2, chemical factors: smoking tobacco oil has benzopyrene, N-nitrosoguanidine and other carcinogenic (especially heavy smokers and alcohol drinkers) chewing tobacco or betel nut is more harmful than smoking. 3.Biological factors: some malignant tumors can be caused by viruses, such as nasopharyngeal carcinoma and malignant lymphoma. 4.Nutritional factors: Oral cancer is related to vitamin A, B and E deficiency. Intrinsic factors 1. Neuropsychiatric factors: many tumor patients have a history of serious mental trauma before the onset of disease, or still maintain abnormal mental state after the onset of disease, with excessive mental tension and psychological imbalance. Endocrine factors: for example, the chance of oral and oropharyngeal cancer after breast cancer and cervical cancer is greatly increased, and the chance of recurrence of breast cancer in female salivary cancer patients is reported to be 8 times higher than that of normal people. 3.Immunity status 4.Heredity: The law of heredity is expressed in the way of “susceptibility”, and the new generation inherits not cancer itself, but an individual quality that is susceptible to cancer, and needs certain environmental factors to develop. 5. Gene mutation: There are oncogenes and anti-oncogenes or oncogenes in human chromosomes. Qiu Gang, Department of Oral and Maxillofacial Surgery, Dalian Stomatological Hospital