To determine whether you have bowel cancer can be determined by family history, clinical manifestations, colonoscopy, pathological examination, tumor markers, CT of chest, abdomen and pelvis, etc. Among them, pathological results are the gold standard for diagnosing bowel cancer. 1. Family history: Bowel cancer has genetic predisposition, and the risk of bowel cancer will be increased if there are immediate family members suffering from bowel cancer. 2. Clinical manifestations: Early stage of bowel cancer has no obvious manifestations, with the progress of the disease, there may be abdominal discomfort, hidden pain, diarrhea, constipation, blood in stools, etc., which are mostly non-specific. Obvious symptoms often appear when the patient is already in the progressive stage, such as abdominal pain, abdominal mass, anemia, emaciation and so on. 3. Enteroscopy: Enteroscopy is the best examination means to determine whether there is intestinal cancer, which can not only observe whether there are lesions in the intestinal mucosa under direct vision, but also take biopsies for pathology examination to further clarify the diagnosis. Early carcinoma in situ can also be treated under endoscopy. 4. Tumor marker test: some patients with intestinal cancer will have elevated tumor markers, but the specificity of tumor markers is low, and it is difficult to diagnose in early stage, thus the diagnostic value is limited. 5. CT of chest, abdomen and pelvis: perfect CT examination can understand the lesions of bowel cancer, whether there is distant metastasis, etc., which is of guiding significance to the staging of bowel cancer. Patients who are suspected of having intestinal cancer due to the occurrence of related high-risk manifestations are recommended to go to hospital as soon as possible for timely improvement of related examinations, especially colonoscopy and pathological examination, so as to exclude or diagnose as soon as possible in order to avoid delaying the condition.