Highly differentiated rectal cancer is not carcinoma in situ, which is a different concept. It is recommended to go to the hospital for examination and diagnosis in time, and if it is diagnosed, it should be treated according to the doctor’s guidance in time. 1. Highly differentiated rectal cancer: it belongs to low-grade malignant adenocarcinoma, and the cancer cells are mainly derived from glandular cells, and according to the differentiation degree of the cancer cells, it can be divided into highly differentiated, moderately differentiated and lowly differentiated types. According to the degree of differentiation, it can be divided into highly differentiated, moderately differentiated and lowly differentiated types. The cancer cells of rectal hyperdifferentiated adenocarcinoma are similar to normal cells, and usually after surgical resection, if the prognosis is good, the five-year survival rate will be higher. 2. Carcinoma in situ: generally refers to the early stage of cancer, at this time, the heterogeneous cells are usually only in the gland or mucosal epithelium, and have not broken through the basement membrane or infiltrated and metastasized, usually after surgical resection, the prognosis is very good, and a better therapeutic effect can be achieved. No matter which kind of cancer you need to pay more attention to, you should go to the hospital for examination in time, and once diagnosed, you should carry out detailed treatment according to the doctor’s instruction in time, without delay, early detection and early treatment.