Eating betel nut can increase the chance of developing oral cancer. Early stage of oral cancer may have no obvious symptoms, some of them may be ulcers or lumps in the oral mucosa, or small hard lumps or fissures on the mucosal surface. Most of these hard lumps or fissures are irregular and the boundary is not very neat. If left untreated, they will rapidly increase in size and infiltrate and adhere to the surrounding and deeper tissues of the mouth. At the early stage of oral cancer, lymph node metastasis in the neck may also appear, initially as a single active lymph node, followed by enlargement of lymph nodes in multiple areas, or lymph nodes infiltrating surrounding tissues and fixing. Very few oral cancers even have swollen lymph nodes in the neck as the first symptom in clinical practice.