To achieve early detection and diagnosis of rectal cancer, we must first popularize the basic knowledge of rectal cancer, let people know about rectal cancer and completely change the misconceptions in thinking and understanding, mainly in the following areas: 1. mistakenly confuse rectal cancer blood in stool with internal hemorrhoid bleeding, and treat it according to internal hemorrhoid for a long time without going to regular hospitals, which delays the disease 2. mistakenly consider the change of bowel habit as intestinal inflammation, and give anti-inflammatory treatment in local clinics, which makes the symptoms better and worse, recurring and repeatedly treating, which delays the disease The symptoms are sometimes good and bad, recurring, repeated treatment and delayed. Secondly, we should also increase the efforts of census, fecal occult blood test can be used as the primary screening means of rectal cancer, and those who are positive will be further examined, and the cancer detection rate of those who are positive without symptoms is more than 1%. In addition, rectal finger examination, as the most important method to diagnose rectal cancer, should be given sufficient attention. Nearly 75% of Chinese rectal cancer is low rectal cancer, which can be palpated during rectal finger examination and can determine the tumor location, distance from anus, tumor size, scope and mobility, etc. Do not rely on instrument examination or be afraid of dirty or omit this important and cheap diagnostic tool. Rectal cancer examination items 1.rectal finger examination: it is the necessary examination step to diagnose rectal cancer. About 80% of rectal cancer patients can be found through rectal finger examination. Hard and uneven masses can be palpated; in advanced stage, narrow intestinal cavity and fixed masses can be palpated. The finger sleeve can see the dirty pus and blood containing feces. 2.Proctoscopy: After rectal finger examination, proctoscopy should be performed to assist in diagnosis under direct vision, to observe the morphology, upper and lower edges and distance from the anal edge of the mass, and to take tissue of the mass for pathological section to determine the nature of the mass and its differentiation degree. If the cancer is located in the middle or upper rectum and cannot be touched by fingers, sigmoidoscopy is a better method. 3.Barium enema and fiber colonoscopy: they are not very helpful to the diagnosis of rectal cancer, so they are not included in the routine examination, but only used to exclude multiple tumors in the colon and rectum. 4.Pelvic magnetic resonance imaging (MRI): to understand the location of the tumor and its relationship with the surrounding adjacent structures, which can help the preoperative clinically accurate staging and the formulation of reasonable comprehensive treatment strategies, such as: surgery or radiotherapy first? 5.CT of abdominopelvic cavity: It can understand the site of tumor, the relationship with adjacent structures, and whether there are metastases around the rectum and other parts of abdominopelvic cavity. It is important for the staging of rectal cancer. 6.CT of chest or chest X-ray: to understand whether there is metastasis in lung, pleura, mediastinal lymph nodes, etc.