Squamous carcinoma is a malignant tumor originated from squamous epithelium. Squamous carcinoma may occur in all tissues and organs with squamous epithelium, such as lung squamous carcinoma, head and neck squamous carcinoma, esophageal squamous carcinoma and so on. If the cells of squamous carcinoma are confined to the mucosal layer and have not yet broken through the basement membrane, that is, they are in the stage of carcinoma in situ, which does not need chemotherapy treatment at this time and can be cured by surgery alone. Even if the cancer cells have broken through the basement membrane or even metastasized to the surrounding lymph nodes, appropriate radiotherapy or observation after surgical excision may be able to control the disease and chemotherapy is not necessarily needed. Only when cancer cells have metastasized to distant lymph nodes or even to distant organs will chemotherapy treatment be needed, and in addition to chemotherapy treatment, combined surgery and radiotherapy may be needed to control the development of the disease.