Early-stage carcinoma in situ can be cured after surgical excision. The so-called carcinoma in situ refers to cancer cells confined to the mucosal layer or submucosal layer, which have not broken through the basement membrane, let alone regional lymph nodes or even distant metastases, and generally belongs to the early stage of cancer. For some in situ cancers, such as skin carcinoma in situ, even without surgery, physical therapy such as laser, high temperature or freezing can basically remove the cancerous tissues and achieve the standard of cure, while for some tumors with high malignancy, such as malignant melanoma, even if the tumor is in the stage of carcinoma in situ, sometimes, given the limitations of detection or treatment methods, chemotherapy or radiotherapy must be given after surgery. Even if the tumor is at the in situ stage, sometimes, due to the limitation of detection or treatment, other treatments such as chemotherapy or radiotherapy are required after surgery to ensure the cure. In conclusion, malignant tumors in the in situ stage have a high hope of cure, which highlights the importance of early detection, early diagnosis and early treatment of cancer.