1.Blood in stool: It is the most common symptom of rectal cancer, but it is often ignored by patients or misdiagnosed as hemorrhoids and delayed treatment, which aggravates the condition. Blood in stool is mostly red or dark red, mixed with mucus and blood of stool or pus and blood, sometimes accompanied by blood clots and necrotic tissue. The above symptoms are caused by the obstruction of blood flow after the proliferation of cancer, necrosis and erosion of tissues, ulceration and infection, and the consequence of ulcer formation. 2.Change of stool habit: Because of the mass and its secretions, it can produce symptoms of intestinal irritation, frequent bowel movements, unpleasant sensation of defecation, urgency and heaviness, but the discharge is mostly mucus and pus-like material, initially these “pseudo-diarrhea” phenomena mostly occur in the early morning shortly after waking up, called morning diarrhea. morningdiarrhea). Later, the number gradually increases, and even at night can not sleep, changing the usual stool habits. 3.Intestinal stenosis and obstruction: The cancer infiltrates around the circumference of the intestinal wall, narrowing the intestinal cavity, especially at the junction of rectum and sigmoid colon, which is mostly a stenotic type of hard cancer and is very likely to cause obstruction. Rectal jug abdomen cancer, because it is mostly ulcerated type, the rectal jug abdomen is wider, and it is estimated that about 1 to 2 years will cause narrow obstruction, thin stool formation, defecation difficulty, constipation, abdominal discomfort, gas and pain. Due to the accumulation of feces, in the upper part of the obstructed sigmoid colon area, sometimes in the left lower abdomen, a striated mass can be found. 4.Anal pain and anal incontinence: If the lower rectal cancer infiltrates the anal canal, it can cause local pain, and if the anal sphincter is involved, it can cause anal incontinence, and pus and blood often flows out and pollutes the underwear; if the cancer is infected or metastasized, it can cause lymph node enlargement in the groin. Invasion of sacral plexus can cause pain in sacral and perineal area, similar to sciatic nerve pain; invasion of bladder and prostate can cause cystitis, urethritis, vesico-rectal fistula and urethro-rectal fistula in women, and vaginal rectal fistula with fecal matter and mucus-pus-blood discharge from vagina. Liver metastasis may cause hepatomegaly, jaundice, ascites and other symptoms, and systemic symptoms may include anemia and other cachexia, and sometimes acute intestinal obstruction, lower gastrointestinal hemorrhage and diffuse peritonitis after perforation. The symptoms of rectal cancer are very complex and diverse, and the accompanying symptoms of frequent, urgent and painful urination will become more and more serious, and the painful parts will spread.