Early stage rectal cancer has a very good prognosis and a high cure rate, with a 5-year survival rate of greater than 90%. What is early stage rectal cancer? Cancer cells invade the mucosa or submucosa, which means that the cancer cells are only in the innermost layer of the rectal wall and have not yet metastasized. As shown in the figure below, the rectal wall is divided into 5 layers from inside to outside, mucosa (T1a) – submucosa (T1b) – muscle layer (T2) – subplasma layer (T3) – plasma layer (T4a). Colorectal cancer staging pattern diagram Early stage rectal cancer is rare in clinical practice, and is basically detected by physical examination or accidentally, because there are no specific symptoms in early stage. After early radical surgery, postoperative adjuvant chemotherapy is not needed because the risk of recurrence itself is very low because there is no lymph node metastasis. Especially in the mucosal lamina propria, there are no lymphatic vessels and no metastatic pathways for cancer cells. Rectal cancer lymph node metastasis pathway pattern But cancer cells invade the submucosa layer (T1b), and there is lymphatic vessel formation in the submucosa layer, which objectively has the risk of metastasis. Although chemotherapy is not required for T1b, there is a certain risk of metastasis recurrence, so regular postoperative review is also required. In clinical practice, we did encounter early-stage rectal cancer with metastasis as well. This is also the reason why domestic and international guidelines still recommend regular review for early-stage rectal cancer.