After people swallow and chew food, it passes through the small intestine first to the right hemicolectum, then to the left hemicolectum, and finally to the rectum. When the food residue reaches the right hemicolectum, obstruction rarely occurs because the right hemicolectum is wider. However, this tumor is often characterized by secondary infection and chronic toxin absorption, so patients with right hemicolectomy often have symptoms such as low fever, night sweats, general weakness and anemia. When the food residue reaches the left hemicolectum, it turns from the original liquid form to semi-solid form. Because the intestinal lumen of the left hemicolectomy is narrower, it is easy to have symptoms of low-level intestinal obstruction such as abdominal distension, abdominal pain and constipation. The rectum is at the end of the gastrointestinal tract, and the early rectal cancer lesions are only on the intestinal mucosa, so there may be no obvious symptoms. However, after the disease gradually aggravates, there can be local irritation symptoms of tumor, which is manifested as increased frequency of stool, from normal 1~2 times per day to 3~4 times or more, and unshaped stool. The tumor may be characterized by increased frequency of stool, from normal to 3~4 or more times a day, unformed stool, anal discomfort, feeling of falling, sometimes vague abdominal pain, sometimes bloody stool, mucus stool, pus and blood stool, incomplete stool, or even urgency, and abdominal distension, lower abdominal discomfort, difficulty in defecation, less stool, or even intestinal type and intestinal tinnitus. If the surrounding tissues and organs are invaded, symptoms of corresponding organ lesions may appear, such as severe local pain when the anal canal is invaded. Invasion of the anal sphincter may lead to fecal incontinence, often with pus and blood spilling out of the anus. Anterior invasion of the urinary tract may result in urinary frequency, painful urination, and difficulty in urination. When the sacral plexus is invaded backward, persistent and severe pain in the sacral and perineal areas, and involving pain in the lower abdomen, lumbar area and thighs will appear. When cancer metastasizes to the liver, there may be symptoms such as hepatomegaly, jaundice and ascites. Late stage patients may have wasting, anemia, edema or cachexia, etc. The incidence of colon and rectal cancer is also significantly higher among young people, in recent years. If relevant symptoms appear, be alert to whether you are suffering from colon or rectal cancer and go to hospital for examination in time. Before a definite diagnosis is made, you should not treat enteritis and dysentery for a long time to avoid delaying the diagnosis. Rectal finger examination, sigmoid colon and rectal microscopy can help in diagnosis.