Do I need colorectal cancer screening? 1. Why do I need colorectal cancer screening? The incidence rate of colorectal cancer in China is on the rise, according to 2020 China Cancer Statistics Report, the incidence rate and mortality rate of colorectal cancer in China rank 2nd and 5th among all malignant tumors, with urban areas higher than rural areas, and most of the patients are in the middle or late stage when they are diagnosed. Tumor screening is an effective way to improve the early diagnosis rate of colorectal cancer, while early diagnosis and early treatment is the key to improve the survival and prognosis of colorectal cancer patients. With the development of medicine, the cancerous process of colorectal cancer is gradually recognized. Colorectal cancer can originate from adenomatous polyps and then progress to cancer, and this process usually takes 5~10 years. National and international studies have shown that removing adenomatous polyps can prevent cancer, but the occurrence of intestinal polyps is often not accompanied by any symptoms and is not easily detected. Through colonoscopy and other means of tumor screening, colorectal polyps can be detected and biopsied so that they can be removed before they become malignant, which can achieve the purpose of preventing colorectal cancer, and for cancerous lesions that can’t be removed colonoscopically, they can be detected as early as possible and undergo surgical and other treatments. Which groups of people need to be screened for colorectal cancer? What kind of screening tools and strategies are scientific? We will introduce them below. 2. Who should do colorectal cancer screening? The incidence of colorectal cancer is higher in people aged 40-65 years old, and there is a trend of rejuvenation. It is usually recommended that colorectal cancer screening should be done at least from the age of 50. However, the occurrence and development of colorectal cancer is related to many risk factors, such as: patients with a history of colorectal malignancy, first-degree relatives with a family history of colorectal malignancy, a history of intestinal adenomas, or patients with long-standing inflammatory bowel disease have a higher risk of colorectal cancer. For these groups, we recommend screening for colorectal cancer starting at age 40, or 10 years earlier than the youngest patient in a first-degree relative. In addition, certain hereditary diseases may cause colorectal cancer in young age, such as Lynch syndrome, familial adenomatous polyposis, hereditary hyperpigmented digestive polyposis syndrome, etc. These patients or high-risk groups should be screened by colonoscopy from young age or even teenager, so as to detect and intervene in early stage. 3. Common methods of colorectal cancer screening (1) Rectal fingerprinting: I put the fingerprinting of rectum in the first place to emphasize its importance, which is often neglected by patients. Rectal cancer accounts for 30%~40% of all colorectal cancers in China. However, during the annual physical examination of the unit, there are always people who find it embarrassing or troublesome and deliberately avoid the examination. For those who have symptoms such as change of bowel habit and blood in stool, this basic examination must be carried out. Through this examination, it can touch the bowel wall with or without nodules, and finger for dark-red blood in stool, so as to find out the rectal lesion. Due to the limitation of the length of the finger, it can only check the rectum which is 7-8cm away from the anus, but 70% of rectal cancers will occur in this area. (2) Fecal occult blood test: also known as fecal occult blood test (OBT for short), blood in stool is a common and specific symptom of colorectal cancer, but in the early stage of the disease, the amount of bleeding is often too small to be detected by the naked eye, and then fecal occult blood test is needed to detect the disease. The traditional fecal occult blood test is susceptible to food influence and cannot easily detect precancerous lesions such as intestinal polyps. Nowadays, fecal immunochemical testing (FIT) is often used to specifically detect human hemoglobin, which has a higher accuracy rate. If fecal occult blood is positive, further colonoscopy is recommended for screening. (3) Colonoscopy: Among the available screening methods, colonoscopy combined with pathology is the gold standard for colorectal cancer diagnosis. The endoscopist can view the whole colorectal situation completely, and take tissue biopsy to further clarify the pathologic diagnosis of the suspicious lesions found, and directly carry out radical treatment under colonoscopy for the pre-cancerous lesions such as polyps and early stage cancers found. (4) Blood tumor marker examination: commonly used blood tumor markers for colorectal cancer include carcinoembryonic antigen (CEA), cancer antigen 19-9 (CA19-9), etc. However, the specificity of tumor markers is not high, and many tumor patients do not have elevated tumor markers, while there are also many benign diseases with elevated tumor markers. Therefore, we can’t rely on high or low tumor markers to determine whether the patient has a tumor or not, not to mention that it can’t be used for early screening, we need to judge whether the patient has a tumor or not based on the patient’s clinical manifestations, and we should actively carry out the examination of fecal occult blood and colonoscopy for patients suspected of intestinal cancer. (5) Fecal DNA test: it is a non-invasive method of detecting cellular DNA changes in fecal samples. It is a new method of screening for colon cancer and has been adopted by some organizations. The method works by looking for certain abnormal portions of DNA from cancer or polyp cells. Colorectal cancer or polyp cells usually have DNA mutations in certain genes, and cells with these mutations often enter the feces, which can be detected by fecal tests. However, there are some problems with this test, such as: expensive price, low detection rate of precancerous lesions, and specificity to be improved. 4.Frequency of colorectal cancer screening As fecal occult blood test is non-invasive, painless, convenient and low cost, it is generally recommended that people who meet the screening age should undergo it once a year, and colonoscopy is recommended if there is a positive test. People with normal fecal occult blood are also recommended to have a colonoscopy every 5 to 10 years, depending on their condition, and a high-quality colonoscopy with good bowel preparation. Colorectal polyps after electrolysis will also have a certain recurrence rate, for a single or 2 benign polyps after electrolysis, at the beginning of the need to review the colonoscopy once a year, for 2 consecutive years of examination without recurrence, after that can be changed to every 3 ~ 5 years to review the colonoscopy; multiple adenomas (greater than 3), diameter greater than 2cm, accompanied by a severe atypical hyperplasia, greater than 1cm broad-based polyps or lateral growth of polyps using a piecemeal resection, should be Review the colonoscopy 3-6 months after polypectomy, and if there is no recurrence in two consecutive reviews, the review can be extended to once in 2 years. With the development of modern medical technology, not only should we not talk about cancer, but we also need to pay attention to tumor screening, through which we can find out the beginning of the disease as early as possible and intervene in the early stage, so as to get a better prognosis.