Early stage of bowel cancer is usually asymptomatic, or the symptoms are not obvious, only discomfort, indigestion, fecal occult blood, etc. With the development of the tumor, the symptoms gradually appear. With the development of cancer, symptoms gradually appear, such as change of bowel habit, abdominal pain, constipation, abdominal mass, intestinal obstruction, etc., accompanied or not accompanied by systemic symptoms such as anemia, fever and emaciation. Tumor can cause changes in affected organs due to metastasis and infiltration. Moreover, the symptomatic manifestations can be different due to different parts of the disease: the main clinical symptoms of right half colon are loss of appetite, nausea, vomiting, anemia, fatigue and abdominal pain; the intestinal lumen of left half colon is narrower than that of right half colon, which is prone to cause complete or partial intestinal obstruction, resulting in change of bowel habit, constipation, blood in stool, diarrhea, abdominal pain, abdominal cramps, abdominal distension, etc.; the main clinical symptoms of rectal cancer are blood in stool, change of defecation habit and obstruction. change of habit and obstruction. In addition, if metastasis occurs in late stage, metastatic symptoms can appear, such as tumor invading surrounding tissues or organs, causing anal incontinence, continuous pain in lower abdomen and lumbosacral region; tumor cells planting and metastasizing to the abdominopelvic cavity, and rectal fingerprinting can find lumps in cystorectal fossa or uterorectal fossa; tumor planting and metastasizing widely in abdominopelvic cavity, forming peritoneal effusion, i.e., ascites; cancer cells metastasizing through lymphatic vessels to lymph nodes, which causing enlargement of lymph nodes; cancer cells metastasize to liver, lungs, bones and other parts of the body through bloodstream, resulting in symptoms such as pain in liver area, dyspepsia, cough, sputum, bone pain and so on.