Sigmoid colon cancer pT3N1M0IIIB belongs to stage 3 cancer, which is intermediate stage sigmoid colon cancer, and it is postoperative pathological staging, because there is N1 indicating that there is metastasis in lymph nodes, and it needs to carry out radiotherapy and chemotherapy after operation, if the patient has the above situation, it is recommended to go to the outpatient clinic of gastrointestinal surgery of the hospital, and standardize the treatment under the correct guidance of the doctor. Stage 3 sigmoid colon cancer staging method, as long as there is regional lymph node metastasis, i.e. N in TNM, such as N1 or N2, and it is not accompanied by distant metastasis M0, no matter the T stage is T1~T4, it belongs to stage 3 sigmoid colon cancer. The causes of stage 3 sigmoid colon cancer include adenomatous polyps, inflammatory bowel disease, family genetic history, age, obesity, smoking and other factors. For the treatment of stage 3 sigmoid colon cancer, fluorouracil, calcium folinate, oxaliplatin, irinotecan and other chemotherapeutic drugs can be applied as prescribed by doctor for adjuvant treatment, and then surgical resection can be performed.