Colon cancer is a relatively common tumor of the digestive system. In clinical practice, patients are often required to undergo multiple tests in order to confirm or exclude colon cancer. So, what are the roles of these tests? And what are the advantages and disadvantages? Today we will explain them one by one. 1. Rectal examination is the most important physical examination method. Because 3/4 of rectal cancers in China are located below the middle part of the rectum, which can be easily touched by the finger clinic, so “finger examination” is an examination means that cannot be omitted to diagnose rectal cancer. 2.Fecal occult blood test can be used as a “screening” method. When the daily bleeding volume of gastrointestinal tract is more than 5ml, this test can be positive, which can indicate gastrointestinal tumor. 3.Serum tumor marker test Similar to gastric cancer, there is no specific tumor marker for colorectal cancer. At present, CEA (carcinoembryonic antigen) and CA19-9 (glycoconjugate antigen 199) are more commonly used, and the sensitivity of the two combined tests reaches 86.3% and the specificity reaches 88.79%. 4.Gas-barium double contrast enema radiography is a common and effective method to diagnose colon cancer. Different forms of cancer can be shown in the X-ray film, and the localization of lesions is better than fiber colonoscopy. 5.B ultrasound, CT and MRI can determine the depth of tumor infiltration into the intestinal wall and whether the adjacent tissues and distant organs are involved. MRI can also detect the lymphatic metastasis of rectal cancer in a more sensitive way, so as to prepare for tumor staging and grading. 6.Fiber colonoscopy is the “most powerful” tool to diagnose colorectal cancer, which can not only directly observe the lesions, but also obtain biopsies to further clarify the pathological diagnosis. Doctor’s tip We hope that you will actively cooperate with the doctor for examination, so that the doctor can consider all the examination results and formulate the most reasonable treatment plan as soon as possible.