Colorectal cancer is currently one of the most common malignant tumors in China, and its incidence has been on the rise in recent years, and tends to be younger. With the popularity of colonoscopy, some colorectal cancers are detected in early stage without symptoms, but most patients are still diagnosed only after symptoms appear. So what are the symptoms that indicate the possibility of colorectal cancer? The following points need to be noted: a. Change of bowel habits The change of bowel habits is mainly manifested as frequent bowel movements and incomplete bowel movements, and some patients show diarrhea, constipation, alternating diarrhea and constipation, and thinning of stool. The specific symptoms are mainly related to the location of the tumor. The right half colon (including: cecum, ascending colon and part of transverse colon) has a wider intestinal lumen, which may manifest as diarrhea or alternating diarrhea and constipation; while the left half colon (including part of transverse colon, descending colon and sigmoid colon) has a relatively narrow intestinal lumen, and the stool is dry due to water absorption, and with the obstruction of the tumor, it often manifests as constipation; for For rectal cancer with lower tumor location, the tumor infection will stimulate the rectum, which can show the symptoms of rectal irritation, such as: frequent bowel movement, incomplete bowel movement, and feeling of anal swelling. Blood in stool is the most common symptom of colorectal cancer. Due to the rich blood supply of colorectal cancer, small blood vessels on the surface of the tumor may bleed when the stool rubs against the tumor, which is usually slow and mixed with the stool. In right hemicolectomy, because the tumor is far away from the anus, it is difficult to find blood visible to the naked eye, and it usually appears as positive occult blood in stool test. Left hemicolectomy and rectal cancer, because the tumor is relatively close to the anus, can be manifested as mucus dark red blood in the stool visible to the naked eye. The bleeding of colorectal cancer is very different from the bleeding of internal hemorrhoid. Internal hemorrhoid is made up of varicose blood vessels in the anus, which will break down and bleed when it is squeezed by stool, and because it is closer to the anal opening and the bleeding volume is relatively large, it can be manifested as dripping or spraying fresh blood after stool discharge. Abdominal distension and pain Abdominal distension is not typical in the manifestation of colorectal cancer, which is often caused by the narrowing of intestinal cavity due to tumor growth and gradual accumulation of feces. In the early stage, abdominal distension is relatively mild and not easy to be detected, and usually accompanied by mild abdominal pain, which is usually intermittent. However, when the tumor develops to a more advanced stage, especially the left hemicolectasis may cause the tumor to block the intestinal cavity and cause the sign of intestinal obstruction, which manifests as continuous abdominal pain and abdominal distension, and gradually worsens, accompanied by nausea, vomiting, and stopping exhaustion and defecation. Abdominal mass If this symptom is found, it often indicates late development of tumor. The mass in abdomen may be the tumor itself, or it may be formed by adhesion between tumor and surrounding tissues, such as large omentum. The masses of colorectal cancer are usually hard in texture and have a slight pressure pain when pressed. Compared to left hemicolectomy cancer, right hemicolectomy cancer often presents as an abdominal mass and is more easily palpable in patients with a flat or concave abdomen. In addition to the more common symptoms mentioned above, there are also some atypical symptoms, such as: weakness, anemia, prolonged low fever, loss of appetite, etc. When these symptoms occur, it is important to sound the alarm inside and go to the hospital in time so as to obtain professional examination and timely diagnosis and treatment.