Clinicians identify the nature of tumor based on the development pattern of the tumor. Generally speaking, the nature of tumor is determined according to the following points: 1. the way of discovery: how it was discovered, whether there was pain when it was discovered; 2. the growth rate: whether the tumor grows fast or slow, if it grows fast, painless, it may be malignant. If it grows slowly, it may be benign if it has been growing for years. However, there is a kind of tumor which is benign at the beginning and becomes malignant when it grows to a certain point. 3. growth mode: whether the tumor has envelope or not, whether the boundary is clear or not, if it is smooth and the envelope is intact, it is more likely to be benign. If there is no envelope and infiltrative growth, it may be malignant; 4. texture: if the lump is hard, it is more likely to be malignant; soft is more likely to be benign; 5. degree of cell differentiation: this is pathological examination, good differentiation is benign, otherwise it is malignant; 6. other things include tissue origin, age and so on. Cancer generally occurs in people over 60 years old. Sarcoma occurs in adolescents.