Squamous cell carcinoma is a common malignant tumor of the oral and maxillofacial region, which can occur in the tongue, gums, cheeks, floor of the mouth, lips and palate. When many patients find swelling in their mouth, they often worry whether they have “oral cancer”. Generally speaking, oral cancer will have the following symptoms: 1. persistent ulcers or lumps: simple oral ulcers can usually heal on their own within two weeks, but if the ulcers do not heal for a long time and keep getting bigger, you need to be alert; 2. associated symptoms: one of the main differences between malignant tumors and benign tumors is that malignant tumors usually have associated symptoms, including obvious pain, numbness in the corresponding parts (e.g. tongue, lips), numbness, etc. Invasion of facial nerve may also cause abnormal facial expression movement; 3. Functional abnormalities: Malignant tumors often invade adjacent tissues and cause functional abnormalities, such as difficulty in opening mouth, loosening or even loss of teeth, inflexible tongue movement, etc. Of course, the diagnosis of oral cancer must be made by a professional oral and maxillofacial surgeon, and a pathological biopsy is needed to make a definite diagnosis.