The human digestive tract is divided into two sections; the upper section is called the upper GI tract and the lower section is called the lower GI tract. The upper GI tract generally refers to the esophagus, stomach and duodenum, while the lower GI tract includes the jejunum, ileum, colon and rectum. The duodenum, jejunum and ileum are all part of the small intestine; the colon and rectum are part of the large intestine. The large intestine starts from the ileocecal valve and ends at the anus, which is the largest intestinal cavity in the human body, hence its name. According to the location and characteristics of the large intestine, we can roughly divide the large intestine into three parts, one is the right half of the colon, the second is the left half of the colon, and the third is the rectum and anus. The rectum is the most terminal part of the human gastrointestinal tract (about 12-15 cm long, and the index finger of a general surgeon is about 10 cm long, and most rectal cancers can be detected by the clinician with finger diagnosis); the anus is the last portal of the large intestine (surrounded by two layers of internal and external sphincter muscles, controlling the excretion of stool), and it is also the first part through which colonoscopy is performed. If the entire digestive tract is compared to a tunnel, the large intestine is the last section of this tunnel. In this tunnel, the chyme passes slowly and finally forms stool in the large intestine and is expelled through the anus. Colon cancer is one of the most common malignant tumors of the gastrointestinal tract, mostly occurring in middle-aged and elderly people over 50 years old, but recently there is also a trend of younger age. In recent years, the incidence of this disease has a rising trend. This may be mainly related to the factors of changing dietary habits: with the increasing standard of living, people’s intake of fine foods, animal fats and proteins has increased, coupled with the accelerated pace of life and shortened eating time, resulting in the body failing to take in sufficient amount of fibrous food, which causes toxic substances to accumulate in the large intestine for a longer period of time, breeding flab and transforming into cancer cells. Since the clinical biological characteristics of young people are different from those of middle-aged and elderly people, the underdiagnosis rate of colorectal cancer in young people is higher, and it is usually found at an advanced stage. Different parts of colorectal cancer have their own special manifestations and symptoms. Once patients find the corresponding manifestations and symptoms, they should seek medical attention as soon as possible. Early detection, early diagnosis and early treatment of colorectal cancer are very important. Because the early treatment of colorectal cancer has good effect, the 5-year survival rate reaches 60%-70%, and some patients can survive for a long time and work normally after surgery. However, if the early treatment opportunity is missed, metastasis to liver or other organs will occur, and then the treatment effect is very unsatisfactory. So far, colonoscopy is still the only examination method that can detect colorectal cancer more accurately, so patients with indications should be examined anyway. Signs of right hemicolectomy: anemia and abdominal pain Patients with right hemicolectomy often present with abdominal masses and also often have symptoms such as anemia, abdominal pain, full extension weakness and emaciation. However, the stool habits of right hemicolectomy patients do not change significantly. However, the bleeding caused by the necrosis and detachment of cancer tissues will not be easily detected by the naked eye because of the fine peristalsis of the cecum and ascending colon, which makes the blood and the thin paste-like surimi evenly mixed. Such long-term chronic blood loss will cause anemia in patients, and at the same time, due to the growth of the tumor, the body consumes a lot of nutrients, and patients will be accompanied by general symptoms of anemia such as weakness, emaciation, dizziness and pallor. Anemia is one of the main symptoms for patients with right hemicolectomy cancer to seek medical treatment. Meanwhile, the tumor invading the intestinal wall can cause hidden pain and even peri-enteritis, and the pain gradually worsens with obstruction symptoms. As the cancer increases, the right side of the abdomen gradually worsens, and even an abdominal mass can be felt. Abdominal pain is also one of the main symptoms for patients with right hemicolectomy to seek medical treatment. As a result, many patients only discover the cancer in their bodies accidentally when they visit the doctor because of anemia or abdominal pain. Fecal occult blood test is also often positive and may appear as the first symptom. Signs of left colon cancer: blood in stool and intestinal obstruction Patients with left colon cancer discover their disease early on themselves. Blood in the stool (blood in the stool) is the most common symptom, accounting for about 75% of cases. This is because when surimi enters the left hemicolectomy from the right hemicolectomy, the water is reabsorbed and the surimi gradually becomes solid stool, which is hard and can easily bleed by rubbing against the cancerous tissue. The blood in stool visible to the naked eye will alert patients and prompt them to seek medical treatment in time. Mucus stool or mucus-purulent stool may also appear. At the same time, dry and formed stools are difficult to pass through the cancerous tumor, making it easier for intestinal obstruction to occur. This is like the deposition of layer after layer of thick dirt on the inner wall of water pipes, blocking the flow of water. For this reason, intestinal obstruction can also be figuratively understood as “pipe blockage”. Signals of rectal cancer: change in bowel habits and stool shape Due to the stimulation of the intestinal tract by cancer, the main manifestation is the increase in the number of stools, from the original one stool a day to several times a day, or even as many as ten or tens of times a day, with only a small amount of blood and mucus stool each time, mostly accompanied by persistent anal cramping and a sense of incomplete defecation; or one stool for several days. The stool becomes thin and deformed: from the original cylindrical shape to the middle of the stool with a hook-like shape. These are the typical symptoms of rectal cancer. Blood in the stool is also the most common symptom of rectal cancer patients. Blood in the stool is mostly bright red or dark red, and it is rare for patients with heavy bleeding, sometimes the blood in the stool contains mucus, blood clots and detached necrotic tissue. Signs of anal cancer: bleeding and pain Bleeding and pain are the main signs of anal cancer. Solid stool, which is hard, can easily rub against cancerous tissues and cause bleeding, and the blood is bright red and does not mix with stool. Anal cancer can invade nerve tissues at an early stage and cause pain, especially when defecating. Patients have fear of defecation, so it is easy to cause constipation.