Generally speaking, colon cancer surgery with fistula, 5 and a half years after surgery, it is normal to discharge something from the anus at intervals, mostly caused by digestive juices secreted by the intestinal wall, but the definitive diagnosis needs to be combined with further examination. First of all, depending on the surgery, the things that may be discharged are different. If a fistula of the small intestine is done, then the discharge may originate from the digestive juices of the colorectum; if a fistula of the sigmoid colon is done, then it may originate from the rectum. In addition to being digestive fluids, it is also possible that leakage may have occurred from a localized inflammatory lesion in the anus. Therefore, when there is a colorectal cancer surgery with fistula, 5 and a half years after the operation, every once in a while the anus will discharge something, it is recommended to go to the hospital in a timely manner, improve further examination, such as physical examination, abdominal ultrasound, etc., to clarify the diagnosis, combined with the doctor’s advice for targeted treatment.